Prime the landing pad for the new video rendering pipeline.

media/base/video_renderer_sink.h

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef MEDIA_BASE_VIDEO_RENDERER_SINK_H_
+#define MEDIA_BASE_VIDEO_RENDERER_SINK_H_
+
+#include <vector>
+
+#include "base/basictypes.h"
+#include "base/logging.h"
+#include "media/base/media_export.h"
+#include "media/base/video_frame.h"
+
+namespace media {
+
+// VideoRendererSink is an interface representing the end-point for rendered
+// video frames.  An implementation is expected to periodically call Render() on
+// a callback object.
+class MEDIA_EXPORT VideoRendererSink {
+ public:
+  class RenderCallback {
+   public:
+    // Returns a VideoFrame for rendering which should be displayed within the
+    // presentation interval [|deadline_min|, |deadline_max|].  Returns NULL if
+    // no frame or no new frame (since the last Render() call) is available for
+    // rendering within the requested interval.  Intervals are expected to be
+    // regular, contiguous, and monotonically increasing.  Irregular intervals
+    // may affect the rendering decisions made by the underlying callback.
+    virtual scoped_refptr<VideoFrame> Render(base::TimeTicks deadline_min,

[DaleCurtis, 2015/04/07 19:58:45]

Since VideoFrameCompositor will need to pump and the actual compositor will one
day want to know the next frame TimeTick estimate. I'm going to add back the
"base::TimeTicks* next_frame_time_hint" which the fake pump will use to
determine the best pump rate.

+                                             base::TimeTicks deadline_max) = 0;
+
+    // Called by the sink when a VideoFrame previously returned via Render() was
+    // not actually rendered.  Must be called before the next Render() call.
+    virtual void OnFrameDropped() = 0;
+
+    // Render() callbacks may be suspended for compositing reasons.  There will

[DaleCurtis, 2015/04/07 19:58:45]

As discussed offline, these don't work since VideoFrameCompositor (or someone
above it) needs to know the current frame -- so it needs to be the one pumping.
I'm going to drop these in favor of going back to the "visible" boolean which is
passed to Render().

+    // be no outstanding Render() callbacks when OnRenderSuspended() is called,
+    // nor any issued until after OnRenderResumed() has returned.
+    virtual void OnRenderResumed() = 0;
+    virtual void OnRenderSuspended() = 0;
+
+    virtual ~RenderCallback() {}
+  };
+
+  // Starts video rendering.  See RenderCallback for more details.
+  virtual void Start(RenderCallback* callback) = 0;
+
+  // Stops video rendering, waits for any outstanding calls to |callback| to
+  // complete before returning.  No new calls to |callback| will be issued after
+  // this method returns.
+  virtual void Stop() = 0;
+
+  // Instead of using a callback driven rendering path, allow clients to paint
+  // frames as they see fit without regard for the compositor.
+  // TODO(dalecurtis): This should be nuked once experiments show the new path
+  // is amazing and the old path is not! http://crbug.com/439548
+  virtual void PaintFrameUsingOldRenderingPath(
+      const scoped_refptr<VideoFrame>& frame) = 0;
+
+  virtual ~VideoRendererSink() {}
+};
+
+}  // namespace media
+
+#endif  // MEDIA_BASE_VIDEO_RENDERER_SINK_H_