[MessageLoop] Add metrics to diagnose delayed task queue issues.

TBR=fdoray@chromium.org

Bug: 850450, 786597
Change-Id: Iaa8a9d713c5202f371b0fd549d140bbe791e4089
Reviewed-on: https://chromium-review.googlesource.com/1094296
Commit-Queue: Gabriel Charette <gab@chromium.org>
Reviewed-by: Gabriel Charette <gab@chromium.org>
Cr-Commit-Position: refs/heads/master@{#565867}

CrOS-Libchrome-Original-Commit: a6b3d9d7242e5625cf85e51892591bc6597c9387

1 files changed, 16 insertions, 0 deletions

diff --git a/base/message_loop/incoming_task_queue.cc b/base/message_loop/incoming_task_queue.cc
index d6f4d640bf..83800d1675 100644
--- a/base/message_loop/incoming_task_queue.cc
+++ b/base/message_loop/incoming_task_queue.cc
@@ -11,6 +11,7 @@
 #include "base/callback_helpers.h"
 #include "base/location.h"
 #include "base/message_loop/message_loop.h"
+#include "base/metrics/histogram_macros.h"
 #include "base/synchronization/waitable_event.h"
 #include "base/time/time.h"
 #include "build/build_config.h"
@@ -84,6 +85,10 @@ bool IncomingTaskQueue::AddToIncomingQueue(const Location& from_here,
     pending_task.is_high_res = true;
   }
 #endif
+
+  if (!delay.is_zero())
+    UMA_HISTOGRAM_LONG_TIMES("MessageLoop.DelayedTaskQueue.PostedDelay", delay);
+
   return PostPendingTask(&pending_task);
 }
 
@@ -126,6 +131,12 @@ void IncomingTaskQueue::RunTask(PendingTask* pending_task) {
   task_annotator_.RunTask("MessageLoop::PostTask", pending_task);
 }
 
+void IncomingTaskQueue::ReportMetricsOnIdle() const {
+  UMA_HISTOGRAM_COUNTS_1M(
+      "MessageLoop.DelayedTaskQueue.PendingTasksCountOnIdle",
+      delayed_tasks_.Size());
+}
+
 IncomingTaskQueue::TriageQueue::TriageQueue(IncomingTaskQueue* outer)
     : outer_(outer) {}
 
@@ -250,6 +261,11 @@ void IncomingTaskQueue::DelayedQueue::Clear() {
     Pop();
 }
 
+size_t IncomingTaskQueue::DelayedQueue::Size() const {
+  DCHECK_CALLED_ON_VALID_SEQUENCE(outer_->sequence_checker_);
+  return queue_.size();
+}
+
 IncomingTaskQueue::DeferredQueue::DeferredQueue(IncomingTaskQueue* outer)
     : outer_(outer) {}