Make --disable-gpu-compositing disable browser compositor as well.

content/browser/gpu/gpu_data_manager_impl_private.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/gpu/gpu_data_manager_impl_private.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/command_line.h"
 #include "base/debug/trace_event.h"
@@ skipping 804 matching lines @@
         gpu_info_.secondary_gpus[ii].active = false;
       }
     }
     gpu_info_.gpu.active = false;
   }
   UpdateGpuInfoHelper();
   return true;
 }
 
 bool GpuDataManagerImplPrivate::CanUseGpuBrowserCompositor() const {
+  if (CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kDisableGpuCompositing))
+    return false;
   if (ShouldUseWarp())
     return true;
   if (ShouldUseSwiftShader())
     return false;
   if (IsFeatureBlacklisted(gpu::GPU_FEATURE_TYPE_GPU_COMPOSITING))
     return false;
   return true;
 }
 
 void GpuDataManagerImplPrivate::BlockDomainFrom3DAPIs(
@@ skipping 270 matching lines @@
 
 void GpuDataManagerImplPrivate::OnGpuProcessInitFailure() {
   gpu_process_accessible_ = false;
   gpu_info_.finalized = true;
   complete_gpu_info_already_requested_ = true;
   // Some observers might be waiting.
   NotifyGpuInfoUpdate();
 }
 
 }  // namespace content