Ensure that the open gl context is current in the DXVA decoder while processing configuration chang…

content/common/gpu/media/dxva_video_decode_accelerator_win.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 "content/common/gpu/media/dxva_video_decode_accelerator_win.h"
 
 #if !defined(OS_WIN)
 #error This file should only be built on Windows.
 #endif   // !defined(OS_WIN)
 
@@ skipping 2814 matching lines @@
     RETURN_ON_HR_FAILURE(E_FAIL, "Failed to detect H.264 stream config",
         E_FAIL);
   }
   *config_changed = config_change_detector_->config_changed();
   return S_OK;
 }
 
 void DXVAVideoDecodeAccelerator::ConfigChanged(
     const Config& config) {
   DCHECK(main_thread_task_runner_->BelongsToCurrentThread());
+  RETURN_AND_NOTIFY_ON_FAILURE(make_context_current_.Run(),

[sandersd (OOO until July 31), 2016/04/04 23:35:46]

Should it be Invalidate() and/or Initialize() that do this?

[ananta, 2016/04/05 00:00:36]

In the general case Invalidate and Initialize get called in the context of the
IPC handler which makes the context current. I added a call to make the context
current in Invalidate as a best effort as it gets called during errors. We don't
need to do this in Initialize. 

For this case DismissStaleBuffers needs the context to be current. Making it
current in the top level call seems like the right way to go.

+    "Failed to make context current", PLATFORM_FAILURE, );
+
   SetState(kConfigChange);
   DismissStaleBuffers(true);

[jbauman, 2016/04/05 00:02:18]

DismissStaleBuffers is called from other places (e.g. directly as a callback),
so we should probably make it current there.

Also, we should probably do this for DeferredDismissStaleBuffer as well. 

[ananta, 2016/04/05 00:22:10]

Done.

   Invalidate();
   Initialize(config_, client_);
   decoder_thread_task_runner_->PostTask(
       FROM_HERE,
       base::Bind(&DXVAVideoDecodeAccelerator::DecodePendingInputBuffers,
                  base::Unretained(this)));
 }
 
 }  // namespace content