MediaStream: Adding VideoTrackRecorder class and unittests

content/renderer/media/media_stream_video_source.cc

Index: content/renderer/media/media_stream_video_source.cc
diff --git a/content/renderer/media/media_stream_video_source.cc b/content/renderer/media/media_stream_video_source.cc
index 8493fe9856c43ea3c6ccc31fadbe0e588c7c826a..1cfd80a6db22aeacfd1688adbaa1f50c6dfbac68 100644
--- a/content/renderer/media/media_stream_video_source.cc
+++ b/content/renderer/media/media_stream_video_source.cc
@@ -104,29 +104,26 @@ void GetDesiredMinAndMaxAspectRatio(
   if (mandatory)
     return;
 
-  GetOptionalConstraintValueAsDouble(
-      constraints,
-      MediaStreamVideoSource::kMinAspectRatio,
-      min_aspect_ratio);
-  GetOptionalConstraintValueAsDouble(
-      constraints,
-      MediaStreamVideoSource::kMaxAspectRatio,
-      max_aspect_ratio);
+  GetOptionalConstraintValueAsDouble(constraints,
+                                     MediaStreamVideoSource::kMinAspectRatio,
+                                     min_aspect_ratio);
+  GetOptionalConstraintValueAsDouble(constraints,
+                                     MediaStreamVideoSource::kMaxAspectRatio,
+                                     max_aspect_ratio);
 }
 
 // Returns true if |constraint| is fulfilled. |format| can be changed by a
 // constraint, e.g. the frame rate can be changed by setting maxFrameRate.
-bool UpdateFormatForConstraint(
-    const blink::WebMediaConstraint& constraint,
-    bool mandatory,
-    media::VideoCaptureFormat* format) {
+bool UpdateFormatForConstraint(const blink::WebMediaConstraint& constraint,
+                               bool mandatory,
+                               media::VideoCaptureFormat* format) {
   DCHECK(format != NULL);
 
   if (!format->IsValid())
     return false;
 
-  std::string constraint_name = constraint.m_name.utf8();
-  std::string constraint_value = constraint.m_value.utf8();
+  const std::string constraint_name = constraint.m_name.utf8();
+  const std::string constraint_value = constraint.m_value.utf8();
 
   if (constraint_name.find(kGooglePrefix) == 0) {
     // These are actually options, not constraints, so they can be satisfied
@@ -192,10 +189,9 @@ bool UpdateFormatForConstraint(
 
 // Removes media::VideoCaptureFormats from |formats| that don't meet
 // |constraint|.
-void FilterFormatsByConstraint(
-    const blink::WebMediaConstraint& constraint,
-    bool mandatory,
-    media::VideoCaptureFormats* formats) {
+void FilterFormatsByConstraint(const blink::WebMediaConstraint& constraint,
+                               bool mandatory,
+                               media::VideoCaptureFormats* formats) {
   DVLOG(3) << "FilterFormatsByConstraint("
            << "{ constraint.m_name = " << constraint.m_name.utf8()
            << "  constraint.m_value = " << constraint.m_value.utf8()
@@ -264,10 +260,10 @@ media::VideoCaptureFormats FilterFormats(
   constraints.getMandatoryConstraints(mandatory);
   constraints.getOptionalConstraints(optional);
   media::VideoCaptureFormats candidates = supported_formats;
-  for (size_t i = 0; i < mandatory.size(); ++i) {
-    FilterFormatsByConstraint(mandatory[i], true, &candidates);
+  for (const auto& constraint : mandatory) {
+    FilterFormatsByConstraint(constraint, true, &candidates);
     if (candidates.empty()) {
-      *unsatisfied_constraint = mandatory[i].m_name;
+      *unsatisfied_constraint = constraint.m_name;
       return candidates;
     }
   }
@@ -281,9 +277,9 @@ media::VideoCaptureFormats FilterFormats(
   // But if a constraint produce zero candidates, the constraint is ignored and
   // the next constraint is tested.
   // http://dev.w3.org/2011/webrtc/editor/getusermedia.html#idl-def-Constraints
-  for (size_t i = 0; i < optional.size(); ++i) {
+  for (const auto& constraint : optional) {
     media::VideoCaptureFormats current_candidates = candidates;
-    FilterFormatsByConstraint(optional[i], false, &current_candidates);
+    FilterFormatsByConstraint(constraint, false, &current_candidates);
     if (!current_candidates.empty())
       candidates = current_candidates;
   }
@@ -314,10 +310,9 @@ const media::VideoCaptureFormat& GetBestFormatBasedOnArea(
 // resolution since higher resolutions cost more in terms of complexity and
 // many cameras have lower frame rate and have more noise in the image at
 // their maximum supported resolution.
-void GetBestCaptureFormat(
-    const media::VideoCaptureFormats& formats,
-    const blink::WebMediaConstraints& constraints,
-    media::VideoCaptureFormat* capture_format) {
+void GetBestCaptureFormat(const media::VideoCaptureFormats& formats,
+                          const blink::WebMediaConstraints& constraints,
+                          media::VideoCaptureFormat* capture_format) {
   DCHECK(!formats.empty());
 
   int max_width;
@@ -367,8 +362,7 @@ void MediaStreamVideoSource::AddTrack(
     const ConstraintsCallback& callback) {
   DCHECK(CalledOnValidThread());
   DCHECK(!constraints.isNull());
-  DCHECK(std::find(tracks_.begin(), tracks_.end(),
-                   track) == tracks_.end());
+  DCHECK(std::find(tracks_.begin(), tracks_.end(), track) == tracks_.end());
   tracks_.push_back(track);
 
   requested_constraints_.push_back(