Tell Graphics3D not to lock on Flush().

ppapi/shared_impl/ppb_video_decoder_shared.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 "ppapi/shared_impl/ppb_video_decoder_shared.h"
 
 #include "base/logging.h"
 #include "gpu/command_buffer/client/gles2_implementation.h"
 #include "ppapi/c/pp_errors.h"
+#include "ppapi/shared_impl/ppb_graphics_3d_shared.h"
 #include "ppapi/shared_impl/resource_tracker.h"
 #include "ppapi/thunk/enter.h"
 
 namespace ppapi {
 
 PPB_VideoDecoder_Shared::PPB_VideoDecoder_Shared(PP_Instance instance)
     : Resource(OBJECT_IS_IMPL, instance),
       graphics_context_(0),
       gles2_impl_(NULL) {
 }
@@ skipping 63 matching lines @@
     int32 bitstream_buffer_id, int32 result) {
   CallbackById::iterator it =
       bitstream_buffer_callbacks_.find(bitstream_buffer_id);
   DCHECK(it != bitstream_buffer_callbacks_.end());
   scoped_refptr<TrackedCallback> cc = it->second;
   bitstream_buffer_callbacks_.erase(it);
   cc->Run(PP_OK);
 }
 
 void PPB_VideoDecoder_Shared::FlushCommandBuffer() {
-  if (gles2_impl_)
+  if (gles2_impl_) {

[Scott Hess - ex-Googler, 2013/01/07 22:41:02]

This looks broadly like what I expected it to look like, BUT I cannot tell if
this is the right place for it.  It seems like the _shared code shouldn't refer
out to proxy-related stuff like this.  Instead maybe ppb_video_decoder_proxy.cc
code should call something like FlushCommandBufferWhileLocked() [or something]
which does the ScopedNoLocking and then calls this FlushCommandBuffer().  Maybe.

Or make FlushCommandBuffer() virtual and do it that way, I do not know.  It just
feels like the proxy-lock-specific code belongs with the _proxy, so that it
doesn't run in the _impl.

+    // To call Flush() we have to tell Graphics3D that we hold the proxy lock.
+    thunk::EnterResource<thunk::PPB_Graphics3D_API, false> enter_g3d(
+        graphics_context_, false);
+    DCHECK(enter_g3d.succeeded());
+    PPB_Graphics3D_Shared* graphics3d =
+        static_cast<PPB_Graphics3D_Shared*>(enter_g3d.object());
+    PPB_Graphics3D_Shared::ScopedNoLocking dont_lock(graphics3d);
     gles2_impl_->Flush();
+  }
 }
 
 }  // namespace ppapi