Added GL_CHROMIUM_trace_marker feature as well as gpu_toplevel markers.

content/browser/renderer_host/render_widget_host_view_android.cc

Index: content/browser/renderer_host/render_widget_host_view_android.cc
diff --git a/content/browser/renderer_host/render_widget_host_view_android.cc b/content/browser/renderer_host/render_widget_host_view_android.cc
index 7bed6a0cf85fc56f9d163f8c1e10424c7d5e315e..baa59c22d398b00120fa36e0477db654f2a06d0c 100644
--- a/content/browser/renderer_host/render_widget_host_view_android.cc
+++ b/content/browser/renderer_host/render_widget_host_view_android.cc
@@ -118,6 +118,9 @@ class GLHelperHolder
   GLHelperHolder();
   static scoped_ptr<WebGraphicsContext3DCommandBufferImpl> CreateContext3D();
 
+  // Whether gpu_toplevel category is enabled.
+  const unsigned char* gpu_trace_top_level_category_;
+
   scoped_ptr<GLHelper> gl_helper_;
   scoped_ptr<WebGraphicsContext3DCommandBufferImpl> context_;
 
@@ -131,10 +134,15 @@ GLHelperHolder* GLHelperHolder::Create() {
   return holder;
 }
 
-GLHelperHolder::GLHelperHolder() {
+GLHelperHolder::GLHelperHolder()
+    : gpu_trace_top_level_category_(TRACE_EVENT_API_GET_CATEGORY_GROUP_ENABLED(
+          TRACE_DISABLED_BY_DEFAULT("gpu_toplevel"))) {
 }
 
 GLHelperHolder::~GLHelperHolder() {
+  if (context_ && *gpu_trace_top_level_category_) {

[vmiura, 2014/12/09 00:18:10]

Check if the category is enabled inside the macros instead of here.  You'll need
to pass the category to END0 as well.

+    TRACE_GPU_EVENT_END0(context_);
+  }
 }
 
 void GLHelperHolder::Initialize() {
@@ -191,9 +199,13 @@ GLHelperHolder::CreateContext3D() {
           url, gpu_channel_host.get(), attrs, lose_context_when_out_of_memory,
           limits, nullptr));
   if (context->InitializeOnCurrentThread()) {
-    context->pushGroupMarkerEXT(
-        base::StringPrintf("CmdBufferImageTransportFactory-%p",
-                           context.get()).c_str());
+    if (*gpu_trace_top_level_category_) {

[vmiura, 2014/12/09 00:18:10]

Same, check if the category is enabled inside the macros instead of here.

+      TRACE_GPU_EVENT_BEGIN0(
+          context,
+          TRACE_DISABLED_BY_DEFAULT("gpu_toplevel"),
+          base::StringPrintf("CmdBufferImageTransportFactory-%p",
+                             context.get()).c_str());
+    }
   } else {
     context.reset();
   }