[Adaptation] Misc tests for processor, input provider and restrictions.

This CL adds miscellaneous unit tests for the
ResourceAdaptationProcessor, the VideoSourceRestrictions comparators and
the VideoStreamInputStateProvider.

Bug: webrtc:11172
Change-Id: If95f69644aaf2b43e3b19d5729bedef0b438c77b
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/174101
Reviewed-by: Evan Shrubsole <eshr@google.com>
Reviewed-by: Ilya Nikolaevskiy <ilnik@webrtc.org>
Commit-Queue: Henrik Boström <hbos@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#31147}

14 files changed, 531 insertions, 18 deletions

diff --git a/call/adaptation/BUILD.gn b/call/adaptation/BUILD.gn
index 94656cf0a9..deac3156d6 100644
--- a/call/adaptation/BUILD.gn
+++ b/call/adaptation/BUILD.gn
@@ -47,8 +47,11 @@ if (rtc_include_tests) {
     testonly = true
 
     sources = [
+      "resource_adaptation_processor_unittest.cc",
       "resource_unittest.cc",
+      "video_source_restrictions_unittest.cc",
       "video_stream_adapter_unittest.cc",
+      "video_stream_input_state_provider_unittest.cc",
     ]
     deps = [
       ":resource_adaptation",
@@ -68,12 +71,16 @@ if (rtc_include_tests) {
     testonly = true
 
     sources = [
+      "test/fake_frame_rate_provider.cc",
+      "test/fake_frame_rate_provider.h",
       "test/fake_resource.cc",
       "test/fake_resource.h",
     ]
     deps = [
       ":resource_adaptation",
+      "../../api/video:video_stream_encoder",
       "../../rtc_base:rtc_base_approved",
+      "../../test:test_support",
     ]
   }
 }
diff --git a/call/adaptation/resource_adaptation_processor_unittest.cc b/call/adaptation/resource_adaptation_processor_unittest.cc
new file mode 100644
index 0000000000..2e26dbec72
--- /dev/null
+++ b/call/adaptation/resource_adaptation_processor_unittest.cc
@@ -0,0 +1,257 @@
+/*
+ *  Copyright (c) 2020 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "call/adaptation/resource_adaptation_processor.h"
+
+#include "api/video/video_adaptation_counters.h"
+#include "call/adaptation/resource.h"
+#include "call/adaptation/resource_adaptation_processor_interface.h"
+#include "call/adaptation/test/fake_frame_rate_provider.h"
+#include "call/adaptation/test/fake_resource.h"
+#include "call/adaptation/video_source_restrictions.h"
+#include "call/adaptation/video_stream_input_state_provider.h"
+#include "test/gtest.h"
+
+namespace webrtc {
+
+namespace {
+
+const int kDefaultFrameRate = 30;
+const int kDefaultFrameSize = 1280 * 720;
+
+class ResourceAdaptationProcessorListenerForTesting
+    : public ResourceAdaptationProcessorListener {
+ public:
+  ResourceAdaptationProcessorListenerForTesting()
+      : restrictions_updated_count_(0),
+        restrictions_(),
+        adaptation_counters_(),
+        reason_(nullptr) {}
+  ~ResourceAdaptationProcessorListenerForTesting() override {}
+
+  size_t restrictions_updated_count() const {
+    return restrictions_updated_count_;
+  }
+  const VideoSourceRestrictions& restrictions() const { return restrictions_; }
+  const VideoAdaptationCounters& adaptation_counters() const {
+    return adaptation_counters_;
+  }
+  const Resource* reason() const { return reason_; }
+
+  // ResourceAdaptationProcessorListener implementation.
+  void OnVideoSourceRestrictionsUpdated(
+      VideoSourceRestrictions restrictions,
+      const VideoAdaptationCounters& adaptation_counters,
+      const Resource* reason) override {
+    ++restrictions_updated_count_;
+    restrictions_ = restrictions;
+    adaptation_counters_ = adaptation_counters;
+    reason_ = reason;
+  }
+
+ private:
+  size_t restrictions_updated_count_;
+  VideoSourceRestrictions restrictions_;
+  VideoAdaptationCounters adaptation_counters_;
+  const Resource* reason_;
+};
+
+class ResourceAdaptationProcessorTest : public ::testing::Test {
+ public:
+  ResourceAdaptationProcessorTest()
+      : frame_rate_provider_(),
+        input_state_provider_(&frame_rate_provider_),
+        resource_("FakeResource"),
+        processor_(&input_state_provider_,
+                   /*encoder_stats_observer=*/&frame_rate_provider_) {
+    processor_.AddAdaptationListener(&processor_listener_);
+    processor_.AddResource(&resource_);
+  }
+  ~ResourceAdaptationProcessorTest() override {
+    processor_.StopResourceAdaptation();
+  }
+
+  void SetInputStates(bool has_input, int fps, int frame_size) {
+    input_state_provider_.OnHasInputChanged(has_input);
+    frame_rate_provider_.set_fps(fps);
+    input_state_provider_.OnFrameSizeObserved(frame_size);
+  }
+
+  void RestrictSource(VideoSourceRestrictions restrictions) {
+    SetInputStates(
+        true, restrictions.max_frame_rate().value_or(kDefaultFrameRate),
+        restrictions.target_pixels_per_frame().has_value()
+            ? restrictions.target_pixels_per_frame().value()
+            : restrictions.max_pixels_per_frame().value_or(kDefaultFrameSize));
+  }
+
+ protected:
+  FakeFrameRateProvider frame_rate_provider_;
+  VideoStreamInputStateProvider input_state_provider_;
+  FakeResource resource_;
+  ResourceAdaptationProcessor processor_;
+  ResourceAdaptationProcessorListenerForTesting processor_listener_;
+};
+
+}  // namespace
+
+TEST_F(ResourceAdaptationProcessorTest, DisabledByDefault) {
+  EXPECT_EQ(DegradationPreference::DISABLED,
+            processor_.degradation_preference());
+  EXPECT_EQ(DegradationPreference::DISABLED,
+            processor_.effective_degradation_preference());
+  SetInputStates(true, kDefaultFrameRate, kDefaultFrameSize);
+  processor_.StartResourceAdaptation();
+  // Adaptation does not happen when disabled.
+  resource_.set_usage_state(ResourceUsageState::kOveruse);
+  EXPECT_EQ(0u, processor_listener_.restrictions_updated_count());
+}
+
+TEST_F(ResourceAdaptationProcessorTest, InsufficientInput) {
+  processor_.SetDegradationPreference(
+      DegradationPreference::MAINTAIN_FRAMERATE);
+  processor_.StartResourceAdaptation();
+  // Adaptation does not happen if input is insufficient.
+  // When frame size is missing (OnFrameSizeObserved not called yet).
+  input_state_provider_.OnHasInputChanged(true);
+  resource_.set_usage_state(ResourceUsageState::kOveruse);
+  EXPECT_EQ(0u, processor_listener_.restrictions_updated_count());
+  // When "has input" is missing.
+  SetInputStates(false, kDefaultFrameRate, kDefaultFrameSize);
+  resource_.set_usage_state(ResourceUsageState::kOveruse);
+  EXPECT_EQ(0u, processor_listener_.restrictions_updated_count());
+  // Note: frame rate cannot be missing, if unset it is 0.
+}
+
+// These tests verify that restrictions are applied, but not exactly how much
+// the source is restricted. This ensures that the VideoStreamAdapter is wired
+// up correctly but not exactly how the VideoStreamAdapter generates
+// restrictions. For that, see video_stream_adapter_unittest.cc.
+TEST_F(ResourceAdaptationProcessorTest,
+       OveruseTriggersRestrictingResolutionInMaintainFrameRate) {
+  processor_.SetDegradationPreference(
+      DegradationPreference::MAINTAIN_FRAMERATE);
+  processor_.StartResourceAdaptation();
+  SetInputStates(true, kDefaultFrameRate, kDefaultFrameSize);
+  resource_.set_usage_state(ResourceUsageState::kOveruse);
+  EXPECT_EQ(1u, processor_listener_.restrictions_updated_count());
+  EXPECT_TRUE(
+      processor_listener_.restrictions().max_pixels_per_frame().has_value());
+}
+
+TEST_F(ResourceAdaptationProcessorTest,
+       OveruseTriggersRestrictingFrameRateInMaintainResolution) {
+  processor_.SetDegradationPreference(
+      DegradationPreference::MAINTAIN_RESOLUTION);
+  processor_.StartResourceAdaptation();
+  SetInputStates(true, kDefaultFrameRate, kDefaultFrameSize);
+  resource_.set_usage_state(ResourceUsageState::kOveruse);
+  EXPECT_EQ(1u, processor_listener_.restrictions_updated_count());
+  EXPECT_TRUE(processor_listener_.restrictions().max_frame_rate().has_value());
+}
+
+TEST_F(ResourceAdaptationProcessorTest,
+       OveruseTriggersRestrictingFrameRateAndResolutionInBalanced) {
+  processor_.SetDegradationPreference(DegradationPreference::BALANCED);
+  processor_.StartResourceAdaptation();
+  SetInputStates(true, kDefaultFrameRate, kDefaultFrameSize);
+  // Adapting multiple times eventually resticts both frame rate and resolution.
+  // Exactly many times we need to adapt depends on BalancedDegradationSettings,
+  // VideoStreamAdapter and default input states. This test requires it to be
+  // achieved within 4 adaptations.
+  for (size_t i = 0; i < 4; ++i) {
+    resource_.set_usage_state(ResourceUsageState::kOveruse);
+    EXPECT_EQ(i + 1, processor_listener_.restrictions_updated_count());
+    RestrictSource(processor_listener_.restrictions());
+  }
+  EXPECT_TRUE(
+      processor_listener_.restrictions().max_pixels_per_frame().has_value());
+  EXPECT_TRUE(processor_listener_.restrictions().max_frame_rate().has_value());
+}
+
+TEST_F(ResourceAdaptationProcessorTest, AwaitingPreviousAdaptation) {
+  processor_.SetDegradationPreference(
+      DegradationPreference::MAINTAIN_FRAMERATE);
+  processor_.StartResourceAdaptation();
+  SetInputStates(true, kDefaultFrameRate, kDefaultFrameSize);
+  resource_.set_usage_state(ResourceUsageState::kOveruse);
+  EXPECT_EQ(1u, processor_listener_.restrictions_updated_count());
+  // If we don't restrict the source then adaptation will not happen again due
+  // to "awaiting previous adaptation". This prevents "double-adapt".
+  resource_.set_usage_state(ResourceUsageState::kOveruse);
+  EXPECT_EQ(1u, processor_listener_.restrictions_updated_count());
+}
+
+TEST_F(ResourceAdaptationProcessorTest, CannotAdaptUpWhenUnrestricted) {
+  processor_.SetDegradationPreference(
+      DegradationPreference::MAINTAIN_FRAMERATE);
+  processor_.StartResourceAdaptation();
+  SetInputStates(true, kDefaultFrameRate, kDefaultFrameSize);
+  resource_.set_usage_state(ResourceUsageState::kUnderuse);
+  EXPECT_EQ(0u, processor_listener_.restrictions_updated_count());
+}
+
+TEST_F(ResourceAdaptationProcessorTest, UnderuseTakesUsBackToUnrestricted) {
+  processor_.SetDegradationPreference(
+      DegradationPreference::MAINTAIN_FRAMERATE);
+  processor_.StartResourceAdaptation();
+  SetInputStates(true, kDefaultFrameRate, kDefaultFrameSize);
+  resource_.set_usage_state(ResourceUsageState::kOveruse);
+  EXPECT_EQ(1u, processor_listener_.restrictions_updated_count());
+  RestrictSource(processor_listener_.restrictions());
+  resource_.set_usage_state(ResourceUsageState::kUnderuse);
+  EXPECT_EQ(2u, processor_listener_.restrictions_updated_count());
+  EXPECT_EQ(VideoSourceRestrictions(), processor_listener_.restrictions());
+}
+
+TEST_F(ResourceAdaptationProcessorTest, ResourcesCanPreventAdaptingUp) {
+  processor_.SetDegradationPreference(
+      DegradationPreference::MAINTAIN_FRAMERATE);
+  processor_.StartResourceAdaptation();
+  SetInputStates(true, kDefaultFrameRate, kDefaultFrameSize);
+  // Adapt down so that we can adapt up.
+  resource_.set_usage_state(ResourceUsageState::kOveruse);
+  EXPECT_EQ(1u, processor_listener_.restrictions_updated_count());
+  RestrictSource(processor_listener_.restrictions());
+  // Adapting up is prevented.
+  resource_.set_is_adaptation_up_allowed(false);
+  resource_.set_usage_state(ResourceUsageState::kUnderuse);
+  EXPECT_EQ(1u, processor_listener_.restrictions_updated_count());
+}
+
+TEST_F(ResourceAdaptationProcessorTest, AdaptingTriggersOnAdaptationApplied) {
+  processor_.SetDegradationPreference(
+      DegradationPreference::MAINTAIN_FRAMERATE);
+  processor_.StartResourceAdaptation();
+  SetInputStates(true, kDefaultFrameRate, kDefaultFrameSize);
+  resource_.set_usage_state(ResourceUsageState::kOveruse);
+  EXPECT_EQ(1u, resource_.num_adaptations_applied());
+}
+
+TEST_F(ResourceAdaptationProcessorTest, AdaptingClearsResourceUsageState) {
+  processor_.SetDegradationPreference(
+      DegradationPreference::MAINTAIN_FRAMERATE);
+  processor_.StartResourceAdaptation();
+  SetInputStates(true, kDefaultFrameRate, kDefaultFrameSize);
+  resource_.set_usage_state(ResourceUsageState::kOveruse);
+  EXPECT_EQ(1u, processor_listener_.restrictions_updated_count());
+  EXPECT_FALSE(resource_.usage_state().has_value());
+}
+
+TEST_F(ResourceAdaptationProcessorTest,
+       FailingAdaptingAlsoClearsResourceUsageState) {
+  processor_.SetDegradationPreference(DegradationPreference::DISABLED);
+  processor_.StartResourceAdaptation();
+  resource_.set_usage_state(ResourceUsageState::kOveruse);
+  EXPECT_EQ(0u, processor_listener_.restrictions_updated_count());
+  EXPECT_FALSE(resource_.usage_state().has_value());
+}
+
+}  // namespace webrtc
diff --git a/call/adaptation/test/fake_frame_rate_provider.cc b/call/adaptation/test/fake_frame_rate_provider.cc
new file mode 100644
index 0000000000..65fee6a7ba
--- /dev/null
+++ b/call/adaptation/test/fake_frame_rate_provider.cc
@@ -0,0 +1,27 @@
+/*
+ *  Copyright (c) 2020 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "call/adaptation/test/fake_frame_rate_provider.h"
+
+#include "test/gmock.h"
+
+using ::testing::Return;
+
+namespace webrtc {
+
+FakeFrameRateProvider::FakeFrameRateProvider() {
+  set_fps(0);
+}
+
+void FakeFrameRateProvider::set_fps(int fps) {
+  EXPECT_CALL(*this, GetInputFrameRate()).WillRepeatedly(Return(fps));
+}
+
+}  // namespace webrtc
diff --git a/call/adaptation/test/fake_frame_rate_provider.h b/call/adaptation/test/fake_frame_rate_provider.h
new file mode 100644
index 0000000000..a08e162321
--- /dev/null
+++ b/call/adaptation/test/fake_frame_rate_provider.h
@@ -0,0 +1,57 @@
+/*
+ *  Copyright (c) 2020 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef CALL_ADAPTATION_TEST_FAKE_FRAME_RATE_PROVIDER_H_
+#define CALL_ADAPTATION_TEST_FAKE_FRAME_RATE_PROVIDER_H_
+
+#include <string>
+#include <vector>
+
+#include "api/video/video_stream_encoder_observer.h"
+#include "test/gmock.h"
+
+namespace webrtc {
+
+class MockVideoStreamEncoderObserver : public VideoStreamEncoderObserver {
+ public:
+  MOCK_METHOD2(OnEncodedFrameTimeMeasured, void(int, int));
+  MOCK_METHOD2(OnIncomingFrame, void(int, int));
+  MOCK_METHOD2(OnSendEncodedImage,
+               void(const EncodedImage&, const CodecSpecificInfo*));
+  MOCK_METHOD1(OnEncoderImplementationChanged, void(const std::string&));
+  MOCK_METHOD1(OnFrameDropped, void(DropReason));
+  MOCK_METHOD2(OnEncoderReconfigured,
+               void(const VideoEncoderConfig&,
+                    const std::vector<VideoStream>&));
+  MOCK_METHOD3(OnAdaptationChanged,
+               void(VideoAdaptationReason,
+                    const VideoAdaptationCounters&,
+                    const VideoAdaptationCounters&));
+  MOCK_METHOD0(ClearAdaptationStats, void());
+  MOCK_METHOD2(UpdateAdaptationSettings,
+               void(AdaptationSettings, AdaptationSettings));
+  MOCK_METHOD0(OnMinPixelLimitReached, void());
+  MOCK_METHOD0(OnInitialQualityResolutionAdaptDown, void());
+  MOCK_METHOD1(OnSuspendChange, void(bool));
+  MOCK_METHOD2(OnBitrateAllocationUpdated,
+               void(const VideoCodec&, const VideoBitrateAllocation&));
+  MOCK_METHOD1(OnEncoderInternalScalerUpdate, void(bool));
+  MOCK_CONST_METHOD0(GetInputFrameRate, int());
+};
+
+class FakeFrameRateProvider : public MockVideoStreamEncoderObserver {
+ public:
+  FakeFrameRateProvider();
+  void set_fps(int fps);
+};
+
+}  // namespace webrtc
+
+#endif  // CALL_ADAPTATION_TEST_FAKE_FRAME_RATE_PROVIDER_H_
diff --git a/call/adaptation/test/fake_resource.cc b/call/adaptation/test/fake_resource.cc
index dc2d8c5df9..bd7ad5431f 100644
--- a/call/adaptation/test/fake_resource.cc
+++ b/call/adaptation/test/fake_resource.cc
@@ -15,7 +15,10 @@
 namespace webrtc {
 
 FakeResource::FakeResource(std::string name)
-    : Resource(), name_(std::move(name)) {}
+    : Resource(),
+      name_(std::move(name)),
+      is_adaptation_up_allowed_(true),
+      num_adaptations_applied_(0) {}
 
 FakeResource::~FakeResource() {}
 
@@ -23,4 +26,28 @@ void FakeResource::set_usage_state(ResourceUsageState usage_state) {
   OnResourceUsageStateMeasured(usage_state);
 }
 
+void FakeResource::set_is_adaptation_up_allowed(bool is_adaptation_up_allowed) {
+  is_adaptation_up_allowed_ = is_adaptation_up_allowed;
+}
+
+size_t FakeResource::num_adaptations_applied() const {
+  return num_adaptations_applied_;
+}
+
+bool FakeResource::IsAdaptationUpAllowed(
+    const VideoStreamInputState& input_state,
+    const VideoSourceRestrictions& restrictions_before,
+    const VideoSourceRestrictions& restrictions_after,
+    const Resource& reason_resource) const {
+  return is_adaptation_up_allowed_;
+}
+
+void FakeResource::OnAdaptationApplied(
+    const VideoStreamInputState& input_state,
+    const VideoSourceRestrictions& restrictions_before,
+    const VideoSourceRestrictions& restrictions_after,
+    const Resource& reason_resource) {
+  ++num_adaptations_applied_;
+}
+
 }  // namespace webrtc
diff --git a/call/adaptation/test/fake_resource.h b/call/adaptation/test/fake_resource.h
index 2e1dc1b550..0d9b1f46bb 100644
--- a/call/adaptation/test/fake_resource.h
+++ b/call/adaptation/test/fake_resource.h
@@ -24,11 +24,24 @@ class FakeResource : public Resource {
   ~FakeResource() override;
 
   void set_usage_state(ResourceUsageState usage_state);
+  void set_is_adaptation_up_allowed(bool is_adaptation_up_allowed);
+  size_t num_adaptations_applied() const;
 
+  // Resource implementation.
   std::string name() const override { return name_; }
+  bool IsAdaptationUpAllowed(const VideoStreamInputState& input_state,
+                             const VideoSourceRestrictions& restrictions_before,
+                             const VideoSourceRestrictions& restrictions_after,
+                             const Resource& reason_resource) const override;
+  void OnAdaptationApplied(const VideoStreamInputState& input_state,
+                           const VideoSourceRestrictions& restrictions_before,
+                           const VideoSourceRestrictions& restrictions_after,
+                           const Resource& reason_resource) override;
 
  private:
   const std::string name_;
+  bool is_adaptation_up_allowed_;
+  size_t num_adaptations_applied_;
 };
 
 }  // namespace webrtc
diff --git a/call/adaptation/video_source_restrictions_unittest.cc b/call/adaptation/video_source_restrictions_unittest.cc
new file mode 100644
index 0000000000..eeb4b1d7fd
--- /dev/null
+++ b/call/adaptation/video_source_restrictions_unittest.cc
@@ -0,0 +1,73 @@
+/*
+ *  Copyright (c) 2020 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "call/adaptation/video_source_restrictions.h"
+
+#include "test/gtest.h"
+
+namespace webrtc {
+
+namespace {
+
+VideoSourceRestrictions RestrictionsFromMaxPixelsPerFrame(
+    size_t max_pixels_per_frame) {
+  return VideoSourceRestrictions(max_pixels_per_frame, absl::nullopt,
+                                 absl::nullopt);
+}
+
+VideoSourceRestrictions RestrictionsFromMaxFrameRate(double max_frame_rate) {
+  return VideoSourceRestrictions(absl::nullopt, absl::nullopt, max_frame_rate);
+}
+
+}  // namespace
+
+TEST(VideoSourceRestrictionsTest, DidIncreaseResolution) {
+  // smaller restrictions -> larger restrictions
+  EXPECT_TRUE(DidIncreaseResolution(RestrictionsFromMaxPixelsPerFrame(10),
+                                    RestrictionsFromMaxPixelsPerFrame(11)));
+  // unrestricted -> restricted
+  EXPECT_FALSE(DidIncreaseResolution(VideoSourceRestrictions(),
+                                     RestrictionsFromMaxPixelsPerFrame(10)));
+  // restricted -> unrestricted
+  EXPECT_TRUE(DidIncreaseResolution(RestrictionsFromMaxPixelsPerFrame(10),
+                                    VideoSourceRestrictions()));
+  // restricted -> equally restricted
+  EXPECT_FALSE(DidIncreaseResolution(RestrictionsFromMaxPixelsPerFrame(10),
+                                     RestrictionsFromMaxPixelsPerFrame(10)));
+  // unrestricted -> unrestricted
+  EXPECT_FALSE(DidIncreaseResolution(VideoSourceRestrictions(),
+                                     VideoSourceRestrictions()));
+  // larger restrictions -> smaller restrictions
+  EXPECT_FALSE(DidIncreaseResolution(RestrictionsFromMaxPixelsPerFrame(10),
+                                     RestrictionsFromMaxPixelsPerFrame(9)));
+}
+
+TEST(VideoSourceRestrictionsTest, DidDecreaseFrameRate) {
+  // samller restrictions -> larger restrictions
+  EXPECT_FALSE(DidDecreaseFrameRate(RestrictionsFromMaxFrameRate(10),
+                                    RestrictionsFromMaxFrameRate(11)));
+  // unrestricted -> restricted
+  EXPECT_TRUE(DidDecreaseFrameRate(VideoSourceRestrictions(),
+                                   RestrictionsFromMaxFrameRate(10)));
+  // restricted -> unrestricted
+  EXPECT_FALSE(DidDecreaseFrameRate(RestrictionsFromMaxFrameRate(10),
+                                    VideoSourceRestrictions()));
+  // restricted -> equally restricted
+  EXPECT_FALSE(DidDecreaseFrameRate(RestrictionsFromMaxFrameRate(10),
+                                    RestrictionsFromMaxFrameRate(10)));
+  // unrestricted -> unrestricted
+  EXPECT_FALSE(DidDecreaseFrameRate(VideoSourceRestrictions(),
+                                    VideoSourceRestrictions()));
+  // larger restrictions -> samller restrictions
+  EXPECT_TRUE(DidDecreaseFrameRate(RestrictionsFromMaxFrameRate(10),
+                                   RestrictionsFromMaxFrameRate(9)));
+}
+
+}  // namespace webrtc
diff --git a/call/adaptation/video_stream_adapter.cc b/call/adaptation/video_stream_adapter.cc
index 62330e945f..b224e3e4d2 100644
--- a/call/adaptation/video_stream_adapter.cc
+++ b/call/adaptation/video_stream_adapter.cc
@@ -433,7 +433,7 @@ Adaptation VideoStreamAdapter::GetAdaptationUp() const {
     }
     case DegradationPreference::MAINTAIN_RESOLUTION: {
       // Scale up framerate.
-      int target_fps = input_state_.frames_per_second().value();
+      int target_fps = input_state_.frames_per_second();
       if (source_restrictor_->adaptation_counters().fps_adaptations == 1) {
         RTC_LOG(LS_INFO) << "Removing framerate down-scaling setting.";
         target_fps = std::numeric_limits<int>::max();
@@ -505,8 +505,7 @@ Adaptation VideoStreamAdapter::GetAdaptationDown() const {
           min_pixel_limit_reached);
     }
     case DegradationPreference::MAINTAIN_RESOLUTION: {
-      int target_fps =
-          GetLowerFrameRateThan(input_state_.frames_per_second().value());
+      int target_fps = GetLowerFrameRateThan(input_state_.frames_per_second());
       if (!source_restrictor_->CanDecreaseFrameRateTo(target_fps)) {
         return Adaptation(adaptation_validation_id_,
                           Adaptation::Status::kLimitReached);
@@ -542,7 +541,7 @@ void VideoStreamAdapter::ApplyAdaptation(const Adaptation& adaptation) {
   // adapting again before this adaptation has had an effect.
   last_adaptation_request_.emplace(AdaptationRequest{
       input_state_.frame_size_pixels().value(),
-      input_state_.frames_per_second().value(),
+      input_state_.frames_per_second(),
       AdaptationRequest::GetModeFromAdaptationAction(adaptation.step().type)});
   // Adapt!
   source_restrictor_->ApplyAdaptationStep(adaptation.step(),
diff --git a/call/adaptation/video_stream_input_state.cc b/call/adaptation/video_stream_input_state.cc
index 1827334b21..dc3315e6d0 100644
--- a/call/adaptation/video_stream_input_state.cc
+++ b/call/adaptation/video_stream_input_state.cc
@@ -17,7 +17,7 @@ namespace webrtc {
 VideoStreamInputState::VideoStreamInputState()
     : has_input_(false),
       frame_size_pixels_(absl::nullopt),
-      frames_per_second_(absl::nullopt),
+      frames_per_second_(0),
       video_codec_type_(VideoCodecType::kVideoCodecGeneric),
       min_pixels_per_frame_(kDefaultMinPixelsPerFrame) {}
 
@@ -30,8 +30,7 @@ void VideoStreamInputState::set_frame_size_pixels(
   frame_size_pixels_ = frame_size_pixels;
 }
 
-void VideoStreamInputState::set_frames_per_second(
-    absl::optional<int> frames_per_second) {
+void VideoStreamInputState::set_frames_per_second(int frames_per_second) {
   frames_per_second_ = frames_per_second;
 }
 
@@ -52,7 +51,7 @@ absl::optional<int> VideoStreamInputState::frame_size_pixels() const {
   return frame_size_pixels_;
 }
 
-absl::optional<int> VideoStreamInputState::frames_per_second() const {
+int VideoStreamInputState::frames_per_second() const {
   return frames_per_second_;
 }
 
@@ -65,8 +64,7 @@ int VideoStreamInputState::min_pixels_per_frame() const {
 }
 
 bool VideoStreamInputState::HasInputFrameSizeAndFramesPerSecond() const {
-  return has_input_ && frame_size_pixels_.has_value() &&
-         frames_per_second_.has_value();
+  return has_input_ && frame_size_pixels_.has_value();
 }
 
 }  // namespace webrtc
diff --git a/call/adaptation/video_stream_input_state.h b/call/adaptation/video_stream_input_state.h
index ef80405e75..af0d7c78e9 100644
--- a/call/adaptation/video_stream_input_state.h
+++ b/call/adaptation/video_stream_input_state.h
@@ -24,13 +24,13 @@ class VideoStreamInputState {
 
   void set_has_input(bool has_input);
   void set_frame_size_pixels(absl::optional<int> frame_size_pixels);
-  void set_frames_per_second(absl::optional<int> frames_per_second);
+  void set_frames_per_second(int frames_per_second);
   void set_video_codec_type(VideoCodecType video_codec_type);
   void set_min_pixels_per_frame(int min_pixels_per_frame);
 
   bool has_input() const;
   absl::optional<int> frame_size_pixels() const;
-  absl::optional<int> frames_per_second() const;
+  int frames_per_second() const;
   VideoCodecType video_codec_type() const;
   int min_pixels_per_frame() const;
 
@@ -39,7 +39,7 @@ class VideoStreamInputState {
  private:
   bool has_input_;
   absl::optional<int> frame_size_pixels_;
-  absl::optional<int> frames_per_second_;
+  int frames_per_second_;
   VideoCodecType video_codec_type_;
   int min_pixels_per_frame_;
 };
diff --git a/call/adaptation/video_stream_input_state_provider.cc b/call/adaptation/video_stream_input_state_provider.cc
index 2548a4802b..eac30bbfac 100644
--- a/call/adaptation/video_stream_input_state_provider.cc
+++ b/call/adaptation/video_stream_input_state_provider.cc
@@ -40,8 +40,7 @@ VideoStreamInputState VideoStreamInputStateProvider::InputState() {
   // GetInputFrameRate() is thread-safe.
   int input_fps = frame_rate_provider_->GetInputFrameRate();
   rtc::CritScope lock(&crit_);
-  input_state_.set_frames_per_second(
-      input_fps >= 0 ? absl::optional<int>(input_fps) : absl::nullopt);
+  input_state_.set_frames_per_second(input_fps);
   return input_state_;
 }
 
diff --git a/call/adaptation/video_stream_input_state_provider_unittest.cc b/call/adaptation/video_stream_input_state_provider_unittest.cc
new file mode 100644
index 0000000000..49c662c581
--- /dev/null
+++ b/call/adaptation/video_stream_input_state_provider_unittest.cc
@@ -0,0 +1,53 @@
+/*
+ *  Copyright (c) 2020 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "call/adaptation/video_stream_input_state_provider.h"
+
+#include <utility>
+
+#include "api/video_codecs/video_encoder.h"
+#include "call/adaptation/encoder_settings.h"
+#include "call/adaptation/test/fake_frame_rate_provider.h"
+#include "test/gtest.h"
+
+namespace webrtc {
+
+TEST(VideoStreamInputStateProviderTest, DefaultValues) {
+  FakeFrameRateProvider frame_rate_provider;
+  VideoStreamInputStateProvider input_state_provider(&frame_rate_provider);
+  VideoStreamInputState input_state = input_state_provider.InputState();
+  EXPECT_EQ(false, input_state.has_input());
+  EXPECT_EQ(absl::nullopt, input_state.frame_size_pixels());
+  EXPECT_EQ(0, input_state.frames_per_second());
+  EXPECT_EQ(VideoCodecType::kVideoCodecGeneric, input_state.video_codec_type());
+  EXPECT_EQ(kDefaultMinPixelsPerFrame, input_state.min_pixels_per_frame());
+}
+
+TEST(VideoStreamInputStateProviderTest, ValuesSet) {
+  FakeFrameRateProvider frame_rate_provider;
+  VideoStreamInputStateProvider input_state_provider(&frame_rate_provider);
+  input_state_provider.OnHasInputChanged(true);
+  input_state_provider.OnFrameSizeObserved(42);
+  frame_rate_provider.set_fps(123);
+  VideoEncoder::EncoderInfo encoder_info;
+  encoder_info.scaling_settings.min_pixels_per_frame = 1337;
+  VideoEncoderConfig encoder_config;
+  encoder_config.codec_type = VideoCodecType::kVideoCodecVP9;
+  input_state_provider.OnEncoderSettingsChanged(EncoderSettings(
+      std::move(encoder_info), std::move(encoder_config), VideoCodec()));
+  VideoStreamInputState input_state = input_state_provider.InputState();
+  EXPECT_EQ(true, input_state.has_input());
+  EXPECT_EQ(42, input_state.frame_size_pixels());
+  EXPECT_EQ(123, input_state.frames_per_second());
+  EXPECT_EQ(VideoCodecType::kVideoCodecVP9, input_state.video_codec_type());
+  EXPECT_EQ(1337, input_state.min_pixels_per_frame());
+}
+
+}  // namespace webrtc
diff --git a/video/adaptation/quality_scaler_resource.cc b/video/adaptation/quality_scaler_resource.cc
index 4369baa092..3f32fa2ce6 100644
--- a/video/adaptation/quality_scaler_resource.cc
+++ b/video/adaptation/quality_scaler_resource.cc
@@ -116,8 +116,8 @@ void QualityScalerResource::OnAdaptationApplied(
       DidDecreaseFrameRate(restrictions_before, restrictions_after)) {
     absl::optional<int> min_diff = BalancedDegradationSettings().MinFpsDiff(
         input_state.frame_size_pixels().value());
-    if (min_diff && input_state.frames_per_second().value() > 0) {
-      int fps_diff = input_state.frames_per_second().value() -
+    if (min_diff && input_state.frames_per_second() > 0) {
+      int fps_diff = input_state.frames_per_second() -
                      restrictions_after.max_frame_rate().value();
       if (fps_diff < min_diff.value()) {
         clear_qp_samples = false;
diff --git a/video/adaptation/video_stream_encoder_resource_manager.h b/video/adaptation/video_stream_encoder_resource_manager.h
index 740865baba..61b1506627 100644
--- a/video/adaptation/video_stream_encoder_resource_manager.h
+++ b/video/adaptation/video_stream_encoder_resource_manager.h
@@ -164,6 +164,9 @@ class VideoStreamEncoderResourceManager
   void ResetActiveCounts();
   std::string ActiveCountsToString() const;
 
+  // TODO(hbos): Consider moving all of the manager's resources into separate
+  // files for testability.
+
   // Does not trigger adaptations, only prevents adapting up based on
   // |active_counts_|.
   class PreventAdaptUpDueToActiveCounts final : public Resource {