Thread annotation of rtc::CriticalSection.

Effectively re-lands r5516 which was reverted because talk/-only
checkouts existed. This now resides in webrtc/base/, so no talk/-only
checkouts should be possible.

This change also enables -Wthread-safety for talk/ and fixes a bug in
talk/media/webrtc/webrtcvideoengine2.cc where a guarded variable was
read without taking the corresponding lock.

R=andresp@webrtc.org, mflodman@webrtc.org, pthatcher@webrtc.org
BUG=

Review URL: https://webrtc-codereview.appspot.com/27569004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@7284 4adac7df-926f-26a2-2b94-8c16560cd09d

4 files changed, 16 insertions, 12 deletions

diff --git a/talk/build/common.gypi b/talk/build/common.gypi
index 57b21af8a9..7ee4224e4e 100644
--- a/talk/build/common.gypi
+++ b/talk/build/common.gypi
@@ -91,6 +91,7 @@
               # LateBindingSymbolTable::TableInfo from
               # latebindingsymboltable.cc.def and remove below flag.
               '-Wno-address-of-array-temporary',
+              '-Wthread-safety',
             ],
           }],
         ],
diff --git a/talk/media/webrtc/webrtcvideoengine2.cc b/talk/media/webrtc/webrtcvideoengine2.cc
index 31f6070b17..26e3079787 100644
--- a/talk/media/webrtc/webrtcvideoengine2.cc
+++ b/talk/media/webrtc/webrtcvideoengine2.cc
@@ -1381,14 +1381,8 @@ void WebRtcVideoChannel2::WebRtcVideoSendStream::InputFrame(
                   << frame->GetHeight();
   // Lock before copying, can be called concurrently when swapping input source.
   rtc::CritScope frame_cs(&frame_lock_);
-  if (!muted_) {
-    ConvertToI420VideoFrame(*frame, &video_frame_);
-  } else {
-    // Create a black frame to transmit instead.
-    CreateBlackFrame(&video_frame_,
-                     static_cast<int>(frame->GetWidth()),
-                     static_cast<int>(frame->GetHeight()));
-  }
+  ConvertToI420VideoFrame(*frame, &video_frame_);
+
   rtc::CritScope cs(&lock_);
   if (stream_ == NULL) {
     LOG(LS_WARNING) << "Capturer inputting frames before send codecs are "
@@ -1400,6 +1394,12 @@ void WebRtcVideoChannel2::WebRtcVideoSendStream::InputFrame(
     LOG(LS_VERBOSE) << "VideoFormat 0x0 set, Dropping frame.";
     return;
   }
+  if (muted_) {
+    // Create a black frame to transmit instead.
+    CreateBlackFrame(&video_frame_,
+                     static_cast<int>(frame->GetWidth()),
+                     static_cast<int>(frame->GetHeight()));
+  }
   // Reconfigure codec if necessary.
   SetDimensions(
       video_frame_.width(), video_frame_.height(), capturer->IsScreencast());
diff --git a/talk/media/webrtc/webrtcvideoengine2.h b/talk/media/webrtc/webrtcvideoengine2.h
index a19abd58d3..18a80d7ad7 100644
--- a/talk/media/webrtc/webrtcvideoengine2.h
+++ b/talk/media/webrtc/webrtcvideoengine2.h
@@ -335,10 +335,12 @@ class WebRtcVideoChannel2 : public rtc::MessageHandler,
     };
 
     void SetCodecAndOptions(const VideoCodecSettings& codec,
-                            const VideoOptions& options);
-    void RecreateWebRtcStream();
+                            const VideoOptions& options)
+        EXCLUSIVE_LOCKS_REQUIRED(lock_);
+    void RecreateWebRtcStream() EXCLUSIVE_LOCKS_REQUIRED(lock_);
     // When |override_max| is false constrain width/height to codec dimensions.
-    void SetDimensions(int width, int height, bool override_max);
+    void SetDimensions(int width, int height, bool override_max)
+        EXCLUSIVE_LOCKS_REQUIRED(lock_);
 
     webrtc::Call* const call_;
     WebRtcVideoEncoderFactory2* const encoder_factory_;
diff --git a/talk/session/media/mediamonitor.h b/talk/session/media/mediamonitor.h
index d549362ad7..89740a8d4c 100644
--- a/talk/session/media/mediamonitor.h
+++ b/talk/session/media/mediamonitor.h
@@ -34,6 +34,7 @@
 #include "webrtc/base/criticalsection.h"
 #include "webrtc/base/sigslot.h"
 #include "webrtc/base/thread.h"
+#include "webrtc/base/thread_annotations.h"
 
 namespace cricket {
 
@@ -77,7 +78,7 @@ class MediaMonitorT : public MediaMonitor {
     media_info_.Clear();
     media_channel_->GetStats(&media_info_);
   }
-  virtual void Update() {
+  virtual void Update() EXCLUSIVE_LOCKS_REQUIRED(crit_) {
     MI stats(media_info_);
     crit_.Leave();
     SignalUpdate(media_channel_, stats);