Canvas capture from inactive tab

content/renderer/media/canvas_capture_handler.cc

Index: content/renderer/media/canvas_capture_handler.cc
diff --git a/content/renderer/media/canvas_capture_handler.cc b/content/renderer/media/canvas_capture_handler.cc
index 634267eb153f612d0acd24f9c742b8edd48e1039..6b1f128adb7d7f257efd626eb7c1697a1075ecec 100644
--- a/content/renderer/media/canvas_capture_handler.cc
+++ b/content/renderer/media/canvas_capture_handler.cc
@@ -11,14 +11,16 @@
 #include "base/macros.h"
 #include "base/rand_util.h"
 #include "base/strings/utf_string_conversions.h"
+#include "content/common/frame_messages.h"
 #include "content/public/renderer/render_thread.h"
 #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 "content/renderer/render_view_impl.h"
 #include "third_party/WebKit/public/platform/WebMediaStreamSource.h"
 #include "third_party/WebKit/public/platform/WebString.h"
+#include "third_party/WebKit/public/web/WebLocalFrame.h"
 #include "third_party/libyuv/include/libyuv.h"
 
 namespace content {
@@ -102,8 +104,14 @@ CanvasCaptureHandler::CanvasCaptureHandler(
     blink::WebMediaStreamTrack* track)
     : ask_for_new_frame_(false),
       size_(size),
+      capturer_count_incremented_(false),
       io_task_runner_(io_task_runner),
       weak_ptr_factory_(this) {
+  blink::WebLocalFrame* const web_frame =
+      blink::WebLocalFrame::frameForCurrentContext();
+  render_view_ =
+      web_frame ? RenderViewImpl::FromWebView(web_frame->view()) : nullptr;
+
   scoped_ptr<media::VideoCapturerSource> video_source(
       new CanvasCaptureHandler::VideoCapturerSource(
           weak_ptr_factory_.GetWeakPtr(), frame_rate));
@@ -114,6 +122,14 @@ CanvasCaptureHandler::~CanvasCaptureHandler() {
   DVLOG(3) << __FUNCTION__;
   DCHECK(thread_checker_.CalledOnValidThread());
   io_task_runner_->DeleteSoon(FROM_HERE, delegate_.release());
+
+  // Handle when this class is destructed before StopVideoCapture() call.
+  if (render_view_ && capturer_count_incremented_) {
+    RenderThread::Get()->Send(
+        new FrameHostMsg_DecrementCapturerCount(render_view_->GetRoutingID()));
+    capturer_count_incremented_ = false;
+  }
+  DCHECK(!capturer_count_incremented_);
 }
 
 // static
@@ -154,6 +170,13 @@ void CanvasCaptureHandler::StartVideoCapture(
   delegate_.reset(new CanvasCaptureHandlerDelegate(new_frame_callback));
   DCHECK(delegate_);
   ask_for_new_frame_ = true;
+
+  if (render_view_) {
+    RenderThread::Get()->Send(
+        new FrameHostMsg_IncrementCapturerCount(render_view_->GetRoutingID()));
+    capturer_count_incremented_ = true;
+  }
+
   running_callback.Run(true);
 }
 
@@ -162,6 +185,12 @@ void CanvasCaptureHandler::StopVideoCapture() {
   DCHECK(thread_checker_.CalledOnValidThread());
   ask_for_new_frame_ = false;
   io_task_runner_->DeleteSoon(FROM_HERE, delegate_.release());
+
+  if (render_view_) {
+    RenderThread::Get()->Send(
+        new FrameHostMsg_DecrementCapturerCount(render_view_->GetRoutingID()));
+    capturer_count_incremented_ = false;
+  }
 }
 
 void CanvasCaptureHandler::CreateNewFrame(const SkImage* image) {