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

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
@@ skipping 133 matching lines @@
       bound_fbo_(0),
       weak_ptr_factory_(ALLOW_THIS_IN_INITIALIZER_LIST(this)),
       initialized_(false),
       parent_(NULL),
       parent_texture_id_(0),
       command_buffer_(NULL),
       gles2_helper_(NULL),
       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.

[darin (slow to review), 2012/08/03 21:16:06]

this is exactly the same logic as in render_view_impl.cc, right?  sounds like
ShouldEnableThreadedCompositing() should be pulled out into a helper function
that lives in content/common/.  threaded_compositor_field_trial.{h,cc}?

+  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
 }
 
 WebGraphicsContext3DCommandBufferImpl::
     ~WebGraphicsContext3DCommandBufferImpl() {
   if (gl_) {
     gl_->SetErrorMessageCallback(NULL);
   }
 
   {
     base::AutoLock lock(g_all_shared_contexts_lock.Get());
@@ skipping 349 matching lines @@
                 "frame", frame_number_);
   frame_number_++;
   // Copies the contents of the off-screen render target into the texture
   // 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.
-  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()));
   }
 #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.
   gl_->Flush();
 #endif
@@ skipping 1022 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);
   }
 }