[Chromecast] Adding pause/resume operations to VideoPlaneController.

chromecast/media/base/video_plane_controller.h

Index: chromecast/media/base/video_plane_controller.h
diff --git a/chromecast/media/base/video_plane_controller.h b/chromecast/media/base/video_plane_controller.h
index 74f91eb5532761cebfc9cb9ebcb514a95fc8a3d3..4c0f53bc67206c1e788e4baa4a9034b31656b734 100644
--- a/chromecast/media/base/video_plane_controller.h
+++ b/chromecast/media/base/video_plane_controller.h
@@ -59,6 +59,17 @@ class VideoPlaneController {
   // no-op.
   void SetGraphicsPlaneResolution(const Size& resolution);
 
+  // After Pause is called, no further calls to VideoPlane::SetGeometry will be
+  // made except for any pending calls already scheduled on the media thread.

[halliwell, 2016/01/12 03:25:07]

Technically, doesn't this mean we're not implementing resource relinquish
correctly?  I.e. we could be saying we've relinquished when there are some
pending calls still?

We could probably follow up on that separately given this addresses the resume
behaviour.

[esum, 2016/01/12 04:51:47]

Ah, so I wasn't sure if this was worth the extra code, but it sounds like it is.
What actually happens if a couple SetGeometry calls on the media thread slip
through after the OEM revokes resources? Is it just implementation dependent?

To fix, my first thought is Pause/Resume become asynchronous, so
CastResource::Acquire/RevokeResource are asynchronous, which complicates the
logic in ResourceManagerImpl even more.

[halliwell, 2016/01/12 15:40:38]

It is implementation-dependent, yes.  I don't think it is worth holding up this
change though.  Remember that we currently don't handle media resource
relinquish in a fine-grained way at all.  In order to release video decoder
resources, we just stop the current application.
I think we should leave this issue for now, but add a TODO.

[esum, 2016/01/15 23:02:28]

Done.

+  // The Set methods will however update cached parameters that will take
+  // effect once the class is resumed. Safe to call multiple times.
+  void Pause();
+  // Makes class active again. Also resets the video plane by posting a call to
+  // VideoPlane::SetGeometry with most recent resolution and geometry parameters
+  // (assuming they are all set). Safe to call multiple times.
+  void Resume();
+  bool is_paused() const;
+
  private:
   class RateLimitedSetVideoPlaneGeometry;
   friend struct base::DefaultSingletonTraits<VideoPlaneController>;
@@ -74,6 +85,8 @@ class VideoPlaneController {
   // VideoPlane::SetGeometry.
   bool HaveDataForSetGeometry() const;
 
+  bool is_paused_;
+
   // Current resolutions
   bool have_output_res_;
   bool have_graphics_res_;