aw: Prevent multiple AddObserver

content/renderer/media/android/stream_texture_factory_synchronous_impl.cc

 // 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.
 
 #include "content/renderer/media/android/stream_texture_factory_synchronous_impl.h"
 
 #include <algorithm>
 
 #include "base/bind.h"
 #include "base/callback.h"
@@ skipping 148 matching lines @@
     const CreateContextProviderCallback& try_create_callback,
     int frame_id)
     : create_context_provider_callback_(try_create_callback),
       context_provider_(create_context_provider_callback_.Run()),
       frame_id_(frame_id),
       observer_(NULL) {}
 
 StreamTextureFactorySynchronousImpl::~StreamTextureFactorySynchronousImpl() {}
 
 StreamTextureProxy* StreamTextureFactorySynchronousImpl::CreateProxy() {
-  if (!context_provider_)
+  bool had_proxy = !!context_provider_;
+  if (!had_proxy)
     context_provider_ = create_context_provider_callback_.Run();
 
   if (!context_provider_)
     return NULL;
 
-  if (observer_)
+  if (observer_ && !had_proxy)
     context_provider_->AddObserver(observer_);
   return new StreamTextureProxyImpl(context_provider_);
 }
 
 void StreamTextureFactorySynchronousImpl::EstablishPeer(int32 stream_id,
                                                         int player_id) {
   DCHECK(context_provider_);
   scoped_refptr<gfx::SurfaceTexture> surface_texture =
       context_provider_->GetSurfaceTexture(stream_id);
   if (surface_texture) {
@@ skipping 40 matching lines @@
 
 void StreamTextureFactorySynchronousImpl::RemoveObserver(
     StreamTextureFactoryContextObserver* obs) {
   DCHECK_EQ(observer_, obs);
   observer_ = NULL;
   if (context_provider_)
     context_provider_->RemoveObserver(obs);
 }
 
 }  // namespace content