Crash Fix (Cast Streaming): Render overlay on copy of source frame.

media/cast/sender/performance_metrics_overlay.h

 // Copyright 2015 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_CAST_SENDER_PERFORMANCE_METRICS_OVERLAY_H_
 #define MEDIA_CAST_SENDER_PERFORMANCE_METRICS_OVERLAY_H_
 
 #include "base/time/time.h"
+#include "media/base/video_frame.h"
 
 // This module provides a display of frame-level performance metrics, rendered
 // in the lower-right corner of a VideoFrame.  It looks like this:
 //
 // +---------------------------------------------------------------------+
 // |                         @@@@@@@@@@@@@@@@@@@@@@@                     |
 // |                 @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@                     |
 // |              @@@@@@@@@@@@@@@@@@@@@@@ @@@@@@@@@@@@                   |
 // |             @@@@@@@@@@@@@                    @@@@                   |
 // |            @@@@@@@@@@                        @@@@                   |
@@ skipping 22 matching lines @@
 // playout delay is 400 ms and low-latency adjustment mode is not active.  The
 // target bitrate for this frame is 4000 kbps."  If there were an exclamation
 // mark (!) after the playout delay number instead of a period (.), it would
 // indicate low-latency adjustment mode is active.  See VideoSender for more
 // details.
 //
 // Line 3: Contains the frame's duration (16.7 milliseconds), resolution, and
 // media timestamp in minutes:seconds.hundredths format.
 
 namespace media {
-
-class VideoFrame;
-
 namespace cast {
 
-// Renders an overlay of frame-level performance metrics in the lower-right
-// corner of the |frame|, as described above.  The verbose logging level for
-// video_frame_overlay.cc determines which lines, if any, are rendered: VLOG
-// level 1 renders the bottom line only, level 2 renders the bottom and middle
-// lines, and level 3 renders all three lines.  So, use the
-// --vmodule=performance_metrics_overlay=3 command line argument to turn on
-// rendering of the entire overlay.
-void MaybeRenderPerformanceMetricsOverlay(base::TimeDelta target_playout_delay,
-                                          bool in_low_latency_mode,
-                                          int target_bitrate,
-                                          int frames_ago,
-                                          double encoder_utilization,
-                                          double lossy_utilization,
-                                          VideoFrame* frame);
+// If the user has requested VideoFrames have a performance metrics overlay
+// rendered on them, this function copies the |source| frame and then renders an
+// overlay on the copy. Frame-level performance metrics will be rendered in the
+// lower-right corner of the frame, as described in the module-level comments
+// above.
+//
+// The verbose logging level for video_frame_overlay.cc determines which lines,
+// if any, are rendered: no VLOG level does nothing, level 1 renders the bottom
+// line only, level 2 renders the bottom and middle lines, and level 3 renders
+// all three lines. So, use the --vmodule=performance_metrics_overlay=3 command
+// line argument to turn on rendering of the entire overlay.
+//
+// Note: If |source| is an unsupported format, or no pixels need to be modified,
+// this function will just return |source|.
+scoped_refptr<VideoFrame> MaybeRenderPerformanceMetricsOverlay(
+    base::TimeDelta target_playout_delay,
+    bool in_low_latency_mode,
+    int target_bitrate,
+    int frames_ago,
+    double encoder_utilization,
+    double lossy_utilization,
+    scoped_refptr<VideoFrame> source);
 
 }  // namespace cast
 }  // namespace media
 
 #endif  // MEDIA_CAST_SENDER_PERFORMANCE_METRICS_OVERLAY_H_