cast: Support for low-latency interactive mode

content/browser/media/capture/web_contents_video_capture_device.cc

Index: content/browser/media/capture/web_contents_video_capture_device.cc
diff --git a/content/browser/media/capture/web_contents_video_capture_device.cc b/content/browser/media/capture/web_contents_video_capture_device.cc
index 3a432d856c068ed7f638913321e573c37922f0ea..c1b357f90e58057db5eae6667e67520857559efd 100644
--- a/content/browser/media/capture/web_contents_video_capture_device.cc
+++ b/content/browser/media/capture/web_contents_video_capture_device.cc
@@ -77,6 +77,7 @@
 #include "content/public/browser/web_contents.h"
 #include "media/base/bind_to_current_loop.h"
 #include "media/base/video_capture_types.h"
+#include "media/base/video_frame_metadata.h"
 #include "media/base/video_util.h"
 #include "media/capture/content/screen_capture_device_core.h"
 #include "media/capture/content/thread_safe_capture_oracle.h"
@@ -361,14 +362,23 @@ void FrameSubscriber::DidCaptureFrame(
   // on success.
   if (success) {
     DCHECK_CURRENTLY_ON(BrowserThread::UI);
+    bool ui_event_detected = false;
+    bool animation_content = true;
     // TODO(isheriff): Unclear if taking a snapshot of cursor here affects user
     // experience in any particular scenarios. Doing it prior to capture may
     // require evaluating region_in_frame in this file.
     if (frame_subscriber_ && frame_subscriber_->cursor_renderer_) {
-      if (frame_subscriber_->cursor_renderer_->SnapshotCursorState(
-              region_in_frame))
-        frame_subscriber_->cursor_renderer_->RenderOnVideoFrame(frame);
+      CursorRenderer* cursor_renderer =
+          frame_subscriber_->cursor_renderer_.get();
+      if (cursor_renderer->SnapshotCursorState(region_in_frame))
+        cursor_renderer->RenderOnVideoFrame(frame);
+      ui_event_detected = cursor_renderer->ui_event_detected();
+      animation_content = frame_subscriber_->oracle_proxy_->IsAnimationActive();
     }
+    frame->metadata()->SetBoolean(media::VideoFrameMetadata::ANIMATION_CONTENT,

[miu, 2015/12/01 21:15:27]

In-line with other comments (video_sender.cc), I think it'd be more powerful to
provide timestamps in the metadata instead of booleans.  Specifically:

1. They should be TimeDeltas on the same timeline as the VideoFrame timestamps
themselves.

2. It seems simplest/sufficient to just make these the timestamp of the last
frame where the condition was true.

3. I'd suggest moving all time-comparison logic into this method so it's clear
they are specific to WCVCD capture.  So, for example, instead of a
ui_event_detected() method, I'd suggest a time_of_last_ui_event() accessor that
returns a TimeTicks.  Likewise, instead of IsAnimationActive(), a
time_animation_was_last_detected() accessor.

4. They metadata entries should not be set if state is unknown (i.e.,
|cursor_renderer| is null).

See other comments...

[Irfan, 2015/12/02 22:32:44]

As discussed will look at moving to a single boolean instead

+                                  animation_content);
+    frame->metadata()->SetBoolean(media::VideoFrameMetadata::USER_INTERACTION,
+                                  ui_event_detected);
   }
   capture_frame_cb.Run(frame, timestamp, success);
 }