Don't allow software fallback for UI compositor on CrOS

content/browser/aura/gpu_process_transport_factory.cc

 // Copyright (c) 2013 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/browser/aura/gpu_process_transport_factory.h"
 
 #include <string>
 
 #include "base/bind.h"
 #include "base/command_line.h"
@@ skipping 167 matching lines @@
 }
 
 scoped_ptr<cc::OutputSurface> GpuProcessTransportFactory::CreateOutputSurface(
     ui::Compositor* compositor, bool software_fallback) {
   PerCompositorData* data = per_compositor_data_[compositor];
   if (!data)
     data = CreatePerCompositorData(compositor);
 
   scoped_refptr<ContextProviderCommandBuffer> context_provider;
 
+  // Software fallback does not happen on Chrome OS.
+#if defined(OS_CHROMEOS)
+  software_fallback = false;
+#endif
+
   CommandLine* command_line = CommandLine::ForCurrentProcess();
   if (!command_line->HasSwitch(switches::kUIEnableSoftwareCompositing) &&
       !software_fallback) {
     context_provider = ContextProviderCommandBuffer::Create(
         GpuProcessTransportFactory::CreateContextCommon(data->surface_id),
         "Compositor");
   }
 
   UMA_HISTOGRAM_BOOLEAN("Aura.CreatedGpuBrowserCompositor", !!context_provider);
 
@@ skipping 294 matching lines @@
                     observer_list_,
                     OnLostResources());
 
   // Kill things that use the shared context before killing the shared context.
   lost_gl_helper.reset();
   lost_offscreen_compositor_contexts = NULL;
   lost_shared_main_thread_contexts  = NULL;
 }
 
 }  // namespace content