Add a flag to allow renderer to use software compositor when GL compositor doesn't work.

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 794 matching lines @@
     prefs->accelerated_compositing_for_video_enabled = false;
 
   // Accelerated video and animation are slower than regular when using
   // SwiftShader. 3D CSS may also be too slow to be worthwhile.
   if (ShouldUseSwiftShader()) {
     prefs->accelerated_compositing_for_video_enabled = false;
     prefs->accelerated_compositing_for_animation_enabled = false;
     prefs->accelerated_compositing_for_3d_transforms_enabled = false;
     prefs->accelerated_compositing_for_plugins_enabled = false;
   }
+
+  if (use_software_compositor_) {
+    prefs->force_compositing_mode = true;
+    prefs->accelerated_compositing_enabled = true;
+    prefs->accelerated_compositing_for_3d_transforms_enabled = true;
+    prefs->accelerated_compositing_for_plugins_enabled = true;
+  }
 }
 
 gpu::GpuSwitchingOption
 GpuDataManagerImplPrivate::GetGpuSwitchingOption() const {
   if (!ui::GpuSwitchingManager::GetInstance()->SupportsDualGpus())
     return gpu::GPU_SWITCHING_OPTION_UNKNOWN;
   return gpu_switching_;
 }
 
 void GpuDataManagerImplPrivate::DisableHardwareAcceleration() {
@@ skipping 132 matching lines @@
     : complete_gpu_info_already_requested_(false),
       gpu_switching_(gpu::GPU_SWITCHING_OPTION_AUTOMATIC),
       observer_list_(new GpuDataManagerObserverList),
       use_swiftshader_(false),
       card_blacklisted_(false),
       update_histograms_(true),
       window_count_(0),
       domain_blocking_enabled_(true),
       owner_(owner),
       display_count_(0),
-      gpu_process_accessible_(true) {
+      gpu_process_accessible_(true),
+      use_software_compositor_(false) {
   DCHECK(owner_);
   CommandLine* command_line = CommandLine::ForCurrentProcess();
   if (command_line->HasSwitch(switches::kDisableAcceleratedCompositing)) {
     command_line->AppendSwitch(switches::kDisableAccelerated2dCanvas);
     command_line->AppendSwitch(switches::kDisableAcceleratedLayers);
   }
   if (command_line->HasSwitch(switches::kDisableGpu))
     DisableHardwareAcceleration();
+  if (command_line->HasSwitch(switches::kEnableSoftwareCompositing))
+    use_software_compositor_ = true;
   if (command_line->HasSwitch(switches::kGpuSwitching)) {
     std::string option_string = command_line->GetSwitchValueASCII(
         switches::kGpuSwitching);
     gpu::GpuSwitchingOption option =
         gpu::StringToGpuSwitchingOption(option_string);
     if (option != gpu::GPU_SWITCHING_OPTION_UNKNOWN)
       gpu_switching_ = option;
   }
 
 #if defined(OS_MACOSX)
@@ skipping 223 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