Add threaded compositing mode to field trial

content/common/gpu/client/webgraphicscontext3d_command_buffer_impl.cc

 // Copyright (c) 2012 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/common/gpu/client/webgraphicscontext3d_command_buffer_impl.h"
 
 #include "third_party/khronos/GLES2/gl2.h"
 #ifndef GL_GLEXT_PROTOTYPES
 #define GL_GLEXT_PROTOTYPES 1
 #endif
 #include "third_party/khronos/GLES2/gl2ext.h"
 
 #include <algorithm>
 #include <set>
 
 #include "base/bind.h"
 #include "base/lazy_instance.h"
 #include "base/string_tokenizer.h"
 #include "base/command_line.h"
 #include "base/debug/trace_event.h"
 #include "base/logging.h"
 #include "base/message_loop.h"
+#include "base/metrics/field_trial.h"
 #include "base/metrics/histogram.h"
 #include "base/synchronization/lock.h"
 #include "content/common/gpu/gpu_memory_allocation.h"
 #include "content/common/gpu/client/gpu_channel_host.h"
 #include "content/common/gpu/gpu_process_launch_causes.h"
+#include "content/public/common/content_constants.h"
 #include "content/public/common/content_switches.h"
 #include "gpu/command_buffer/client/gles2_cmd_helper.h"
 #include "gpu/command_buffer/client/gles2_implementation.h"
 #include "gpu/command_buffer/client/gles2_lib.h"
 #include "gpu/command_buffer/client/transfer_buffer.h"
 #include "gpu/command_buffer/common/constants.h"
 #include "gpu/ipc/command_buffer_proxy.h"
 #include "webkit/glue/gl_bindings_skia_cmd_buffer.h"
 
 static base::LazyInstance<base::Lock>::Leaky
@@ skipping 477 matching lines @@
   // used by the compositor.
   if (ShouldUseSwapClient())
     swap_client_->OnViewContextSwapBuffersPosted();
 
   if (command_buffer_->GetLastState().error == gpu::error::kNoError)
     gl_->SwapBuffers();
 
   bool use_echo_for_swap_ack = true;
 #if defined(OS_MACOSX) || defined(OS_WIN)
   // Get ViewMsg_SwapBuffers_ACK from browser for single-threaded path.
-  use_echo_for_swap_ack =
-      CommandLine::ForCurrentProcess()->HasSwitch(
-          switches::kEnableThreadedCompositing) &&
-      !CommandLine::ForCurrentProcess()->HasSwitch(
-          switches::kDisableThreadedCompositing);
+  base::FieldTrial* trial =
+      base::FieldTrialList::Find(content::kGpuCompositingFieldTrialName);
+  bool thread_trial = trial && trial->group_name() ==
+      content::kGpuCompositingFieldTrialThreadEnabledName;
+  use_echo_for_swap_ack = thread_trial ||
+      (CommandLine::ForCurrentProcess()->HasSwitch(
+           switches::kEnableThreadedCompositing) &&
+       !CommandLine::ForCurrentProcess()->HasSwitch(
+           switches::kDisableThreadedCompositing));
 #endif
   if (use_echo_for_swap_ack) {
     command_buffer_->Echo(base::Bind(
         &WebGraphicsContext3DCommandBufferImpl::OnSwapBuffersComplete,
         weak_ptr_factory_.GetWeakPtr()));
   }
 #if defined(OS_MACOSX)
   // It appears that making the compositor's on-screen context current on
   // other platforms implies this flush. TODO(kbr): this means that the
   // TOUCH build and, in the future, other platforms might need this.
@@ skipping 1020 matching lines @@
     swap_client_->OnViewContextSwapBuffersAborted();
 }
 
 void WebGraphicsContext3DCommandBufferImpl::OnErrorMessage(
     const std::string& message, int id) {
   if (error_message_callback_) {
     WebKit::WebString str = WebKit::WebString::fromUTF8(message.c_str());
     error_message_callback_->onErrorMessage(str, id);
   }
 }