Disable Pepper 3d contexts when accelerated compositing of plugins is disabled

chrome/renderer/pepper_plugin_delegate_impl.cc

 // Copyright (c) 2011 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 "chrome/renderer/pepper_plugin_delegate_impl.h"
 
 #include <cmath>
 
 #include "app/l10n_util.h"
 #include "app/surface/transport_dib.h"
@@ skipping 497 matching lines @@
   if (!dib)
     return NULL;
 #endif
 
   return new PlatformImage2DImpl(width, height, dib);
 }
 
 webkit::ppapi::PluginDelegate::PlatformContext3D*
     PepperPluginDelegateImpl::CreateContext3D() {
 #ifdef ENABLE_GPU
+  // If accelerated compositing of plugins is disabled, fail to create a 3D
+  // context, because it won't be visible. This allows graceful fallback in the
+  // modules.
+  if (!render_view_->webkit_preferences().accelerated_plugins_enabled)
+    return NULL;
   WebGraphicsContext3DCommandBufferImpl* context =
       static_cast<WebGraphicsContext3DCommandBufferImpl*>(
           render_view_->webview()->graphicsContext3D());
   if (!context)
     return NULL;
 
   ggl::Context* parent_context = context->context();
   if (!parent_context)
     return NULL;
 
@@ skipping 341 matching lines @@
 }
 
 void PepperPluginDelegateImpl::DidStopLoading() {
   render_view_->DidStopLoadingForPlugin();
 }
 
 void PepperPluginDelegateImpl::SetContentRestriction(int restrictions) {
   render_view_->Send(new ViewHostMsg_UpdateContentRestrictions(
       render_view_->routing_id(), restrictions));
 }