Add UMA histograms for CanvasCaptureHandler

BUG=524218

Review URL: https://codereview.chromium.org/1564243002

Cr-Commit-Position: refs/heads/master@{#368409}

6 files changed, 37 insertions, 11 deletions

diff --git a/content/renderer/media/canvas_capture_handler.cc b/content/renderer/media/canvas_capture_handler.cc
index 9da03dd..634267e 100644
--- a/content/renderer/media/canvas_capture_handler.cc
+++ b/content/renderer/media/canvas_capture_handler.cc
@@ -15,6 +15,7 @@
 #include "content/renderer/media/media_stream_video_capturer_source.h"
 #include "content/renderer/media/media_stream_video_source.h"
 #include "content/renderer/media/media_stream_video_track.h"
+#include "content/renderer/media/webrtc_uma_histograms.h"
 #include "content/renderer/render_thread_impl.h"
 #include "third_party/WebKit/public/platform/WebMediaStreamSource.h"
 #include "third_party/WebKit/public/platform/WebString.h"
@@ -115,6 +116,19 @@ CanvasCaptureHandler::~CanvasCaptureHandler() {
   io_task_runner_->DeleteSoon(FROM_HERE, delegate_.release());
 }
 
+// static
+CanvasCaptureHandler* CanvasCaptureHandler::CreateCanvasCaptureHandler(
+    const blink::WebSize& size,
+    double frame_rate,
+    const scoped_refptr<base::SingleThreadTaskRunner>& io_task_runner,
+    blink::WebMediaStreamTrack* track) {
+  // Save histogram data so we can see how much CanvasCapture is used.
+  // The histogram counts the number of calls to the JS API.
+  UpdateWebRTCMethodCount(WEBKIT_CANVAS_CAPTURE_STREAM);
+
+  return new CanvasCaptureHandler(size, frame_rate, io_task_runner, track);
+}
+
 void CanvasCaptureHandler::sendNewFrame(const SkImage* image) {
   DCHECK(thread_checker_.CalledOnValidThread());
   CreateNewFrame(image);
diff --git a/content/renderer/media/canvas_capture_handler.h b/content/renderer/media/canvas_capture_handler.h
index f080fd1..c9aa313 100644
--- a/content/renderer/media/canvas_capture_handler.h
+++ b/content/renderer/media/canvas_capture_handler.h
@@ -34,16 +34,14 @@ namespace content {
 class CONTENT_EXPORT CanvasCaptureHandler final
     : public NON_EXPORTED_BASE(blink::WebCanvasCaptureHandler) {
  public:
-  // A VideoCapturerSource instance is created, which is responsible for handing
-  // stop&start callbacks back to CanvasCaptureHandler. That VideoCapturerSource
-  // is then plugged into a MediaStreamTrack passed as |track|, and it is owned
-  // by the Blink side MediaStreamSource.
-  CanvasCaptureHandler(
+  ~CanvasCaptureHandler() override;
+
+  // Creates a CanvasCaptureHandler instance and updates UMA histogram.
+  static CanvasCaptureHandler* CreateCanvasCaptureHandler(
       const blink::WebSize& size,
       double frame_rate,
       const scoped_refptr<base::SingleThreadTaskRunner>& io_task_runner,
       blink::WebMediaStreamTrack* track);
-  ~CanvasCaptureHandler() override;
 
   // blink::WebCanvasCaptureHandler Implementation.
   void sendNewFrame(const SkImage* image) override;
@@ -59,6 +57,16 @@ class CONTENT_EXPORT CanvasCaptureHandler final
   blink::WebSize GetSourceSize() const { return size_; }
 
  private:
+  // A VideoCapturerSource instance is created, which is responsible for handing
+  // stop&start callbacks back to CanvasCaptureHandler. That VideoCapturerSource
+  // is then plugged into a MediaStreamTrack passed as |track|, and it is owned
+  // by the Blink side MediaStreamSource.
+  CanvasCaptureHandler(
+      const blink::WebSize& size,
+      double frame_rate,
+      const scoped_refptr<base::SingleThreadTaskRunner>& io_task_runner,
+      blink::WebMediaStreamTrack* track);
+
   void CreateNewFrame(const SkImage* image);
   void AddVideoCapturerSourceToVideoTrack(
       scoped_ptr<media::VideoCapturerSource> source,
diff --git a/content/renderer/media/canvas_capture_handler_unittest.cc b/content/renderer/media/canvas_capture_handler_unittest.cc
index 4bbe54d..6f23ed1 100644
--- a/content/renderer/media/canvas_capture_handler_unittest.cc
+++ b/content/renderer/media/canvas_capture_handler_unittest.cc
@@ -42,10 +42,11 @@ class CanvasCaptureHandlerTest : public Test {
   CanvasCaptureHandlerTest() {}
 
   void SetUp() override {
-    canvas_capture_handler_.reset(new CanvasCaptureHandler(
-        blink::WebSize(kTestCanvasCaptureWidth, kTestCanvasCaptureHeight),
-        kTestCanvasCaptureFramesPerSecond, message_loop_.task_runner(),
-        &track_));
+    canvas_capture_handler_.reset(
+        CanvasCaptureHandler::CreateCanvasCaptureHandler(
+            blink::WebSize(kTestCanvasCaptureWidth, kTestCanvasCaptureHeight),
+            kTestCanvasCaptureFramesPerSecond, message_loop_.task_runner(),
+            &track_));
   }
 
   void TearDown() override {
diff --git a/content/renderer/media/webrtc_uma_histograms.h b/content/renderer/media/webrtc_uma_histograms.h
index 39e703c..c4a5f05 100644
--- a/content/renderer/media/webrtc_uma_histograms.h
+++ b/content/renderer/media/webrtc_uma_histograms.h
@@ -39,6 +39,7 @@ enum JavaScriptAPIName {
   WEBKIT_RTC_PEER_CONNECTION,
   WEBKIT_GET_MEDIA_DEVICES,
   WEBKIT_MEDIA_STREAM_RECORDER,
+  WEBKIT_CANVAS_CAPTURE_STREAM,
   INVALID_NAME
 };
 
diff --git a/content/renderer/renderer_blink_platform_impl.cc b/content/renderer/renderer_blink_platform_impl.cc
index 2bffb25..b823677 100644
--- a/content/renderer/renderer_blink_platform_impl.cc
+++ b/content/renderer/renderer_blink_platform_impl.cc
@@ -933,7 +933,7 @@ WebCanvasCaptureHandler* RendererBlinkPlatformImpl::createCanvasCaptureHandler(
     double frame_rate,
     WebMediaStreamTrack* track) {
 #if defined(ENABLE_WEBRTC)
-  return new CanvasCaptureHandler(
+  return CanvasCaptureHandler::CreateCanvasCaptureHandler(
       size, frame_rate, RenderThread::Get()->GetIOMessageLoopProxy(), track);
 #else
   return nullptr;
diff --git a/tools/metrics/histograms/histograms.xml b/tools/metrics/histograms/histograms.xml
index 8eded3c..1ce9ebc 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -55658,6 +55658,7 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
 <histogram name="WebRTC.webkitApiCount" enum="JavaScriptAPIName">
   <owner>perkj@chromium.org</owner>
   <owner>mcasas@chromium.org</owner>
+  <owner>emircan@chromium.org</owner>
   <summary>Counts number of calls to WebRTC APIs from JavaScript.</summary>
 </histogram>
 
@@ -68115,6 +68116,7 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <int value="3" label="RTCPeerConnection"/>
   <int value="4" label="GetMediaDevices"/>
   <int value="5" label="MediaStreamRecorder"/>
+  <int value="6" label="CanvasCaptureStream"/>
 </enum>
 
 <enum name="KeyboardControlEvent" type="int">