initialize trace_event hooks in angle on gpu startup

content/gpu/gpu_main.cc

Index: content/gpu/gpu_main.cc
diff --git a/content/gpu/gpu_main.cc b/content/gpu/gpu_main.cc
index eeaa11b08c1cac214c37a6cb7c5a6bd02f216a54..8d8274945e66a58f36d770a7815990aa6961efc7 100644
--- a/content/gpu/gpu_main.cc
+++ b/content/gpu/gpu_main.cc
@@ -38,6 +38,7 @@
 #include "base/win/scoped_com_initializer.h"
 #include "content/common/gpu/media/dxva_video_decode_accelerator.h"
 #include "sandbox/win/src/sandbox.h"
+#include "third_party/angle_dx11/src/common/event_tracer.h"
 #elif defined(OS_CHROMEOS) && defined(ARCH_CPU_ARMEL) && defined(USE_X11)
 #include "content/common/gpu/media/exynos_video_decode_accelerator.h"
 #elif defined(OS_CHROMEOS) && defined(ARCH_CPU_X86_FAMILY) && defined(USE_X11)
@@ -79,6 +80,31 @@ bool GpuProcessLogMessageHandler(int severity,
   return false;
 }
 
+const unsigned char* AngleGetTraceCategoryEnabledFlag(const char* name) {
+  return TRACE_EVENT_API_GET_CATEGORY_GROUP_ENABLED(name);
+}
+
+void AngleAddTraceEvent(char phase,
+                        const unsigned char* category_group_enabled,
+                        const char* name,
+                        unsigned long long id,
+                        int num_args,
+                        const char** arg_names,
+                        const unsigned char* arg_types,
+                        const unsigned long long* arg_values,
+                        unsigned char flags) {
+  TRACE_EVENT_API_ADD_TRACE_EVENT(phase,
+                                  category_group_enabled,
+                                  name,
+                                  id,
+                                  num_args,
+                                  arg_names,
+                                  arg_types,
+                                  arg_values,
+                                  NULL,
+                                  flags);
+}
+
 }  // namespace anonymous
 
 // Main function for starting the Gpu process.
@@ -87,6 +113,8 @@ int GpuMain(const MainFunctionParams& parameters) {
   base::debug::TraceLog::GetInstance()->SetProcessName("GPU Process");
   base::debug::TraceLog::GetInstance()->SetProcessSortIndex(
       kTraceEventGpuProcessSortIndex);
+  gl::SetTraceFunctionPointers(&AngleGetTraceCategoryEnabledFlag,

[apatrick_chromium, 2013/08/12 19:34:13]

Does this really work? ANGLE is dynamically loaded. Also what if we're using
OpenGL or Mesa instead of ANGLE? Also, what about platforms other than Windows?

+                               &AngleAddTraceEvent);
 
   const CommandLine& command_line = parameters.command_line;
   if (command_line.HasSwitch(switches::kGpuStartupDialog)) {