WebRTC: One WebRTC Video can have both SW and HW VideoFrame.

media/filters/skcanvas_video_renderer.cc

 // Copyright (c) 2012 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.
 
 #include "media/filters/skcanvas_video_renderer.h"
 
 #include "gpu/GLES2/gl2extchromium.h"
 #include "gpu/command_buffer/client/gles2_interface.h"
 #include "gpu/command_buffer/common/mailbox_holder.h"
 #include "media/base/video_frame.h"
@@ skipping 411 matching lines @@
     canvas->drawRect(dest, paint);
     canvas->flush();
     return;
   }
 
   SkBitmap* target_frame = nullptr;
   if (canvas->getGrContext()) {
     if (accelerated_last_frame_.isNull() ||
         video_frame->timestamp() != accelerated_last_frame_timestamp_) {
       if (video_frame->format() == VideoFrame::NATIVE_TEXTURE) {
+        // Draw HW Video on HW Canvas.
         DCHECK(context_3d.gl);
         DCHECK(context_3d.gr_context);
-        // Draw HW Video on HW Canvas.
-        DCHECK(!accelerated_generator_);
+        if (accelerated_generator_) {
+          // Reset SkBitmap used in SWVideo-to-HWCanvas path.
+          accelerated_last_frame_.reset();
+          accelerated_generator_ = nullptr;
+        }
         if (!CopyVideoFrameTextureToSkBitmapTexture(
                 video_frame.get(), &accelerated_last_frame_, context_3d)) {
           NOTREACHED();
           return;
         }
       } else {
         // Draw SW Video on HW Canvas.
+        if (!accelerated_generator_ && !accelerated_last_frame_.isNull()) {
+          // Reset SkBitmap used in HWVideo-to-HWCanvas path.
+          accelerated_last_frame_.reset();

[DaleCurtis, 2015/01/12 20:47:01]

Can you explain why you need these conditionals? It seems like you could just
put:

  accelerated_last_frame_.reset();
  accelerated_generator_ = nullptr;

between line 430 and 431 and call it done?

[dshwang, 2015/01/13 08:38:22]

That's good question. It's because allocating accelerated_last_frame_is
expensive. We want to reuse texture or system memory belonging to
accelerated_last_frame instead of allocating every frame.

+        }
         accelerated_generator_ = new VideoImageGenerator(video_frame);
 
         // Note: This takes ownership of |accelerated_generator_|.
         if (!SkInstallDiscardablePixelRef(accelerated_generator_,
                                           &accelerated_last_frame_)) {
           NOTREACHED();
           return;
         }
       }
       DCHECK(video_frame->visible_rect().width() ==
@@ skipping 130 matching lines @@
   last_frame_timestamp_ = media::kNoTimestamp();
 }
 
 void SkCanvasVideoRenderer::ResetAcceleratedLastFrame() {
   accelerated_last_frame_.reset();
   accelerated_generator_ = nullptr;
   accelerated_last_frame_timestamp_ = media::kNoTimestamp();
 }
 
 }  // namespace media