Cleaning up compositing field trial code and enable FCM in beta/stable

content/common/gpu/client/webgraphicscontext3d_command_buffer_impl.cc

Index: content/common/gpu/client/webgraphicscontext3d_command_buffer_impl.cc
diff --git a/content/common/gpu/client/webgraphicscontext3d_command_buffer_impl.cc b/content/common/gpu/client/webgraphicscontext3d_command_buffer_impl.cc
index 4cf413d69ed01f9fe61e3fcfb29ccc15d87fd324..6c42c077d5f2e3afe22203c61c4965f2b39176ce 100644
--- a/content/common/gpu/client/webgraphicscontext3d_command_buffer_impl.cc
+++ b/content/common/gpu/client/webgraphicscontext3d_command_buffer_impl.cc
@@ -26,6 +26,7 @@
 #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/compositor_util.h"
 #include "content/public/common/content_constants.h"
 #include "content/public/common/content_switches.h"
 #include "gpu/command_buffer/client/gles2_cmd_helper.h"
@@ -151,7 +152,12 @@ WebGraphicsContext3DCommandBufferImpl::WebGraphicsContext3DCommandBufferImpl(
       transfer_buffer_(NULL),
       gl_(NULL),
       frame_number_(0),
-      bind_generates_resources_(false) {
+      bind_generates_resources_(false),
+      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_ = content::IsThreadedCompositingEnabled();
+#endif
 }
 
 WebGraphicsContext3DCommandBufferImpl::
@@ -521,20 +527,7 @@ void WebGraphicsContext3DCommandBufferImpl::prepareTexture() {
   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.
-  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) {
+  if (use_echo_for_swap_ack_) {
     command_buffer_->Echo(base::Bind(
         &WebGraphicsContext3DCommandBufferImpl::OnSwapBuffersComplete,
         weak_ptr_factory_.GetWeakPtr()));