Re-land: gpu: Add CHROMIUM_sync_query extension.

gpu/command_buffer/service/feature_info.cc

Index: gpu/command_buffer/service/feature_info.cc
diff --git a/gpu/command_buffer/service/feature_info.cc b/gpu/command_buffer/service/feature_info.cc
index 66e6a54eaf159cf2bbea2df0e026c8351eba4f2e..5e65f6de06c34e77f1bc2daa94e2c35a88ee32dd 100644
--- a/gpu/command_buffer/service/feature_info.cc
+++ b/gpu/command_buffer/service/feature_info.cc
@@ -134,8 +134,8 @@ FeatureInfo::FeatureFlags::FeatureFlags()
       is_angle(false),
       is_swiftshader(false),
       angle_texture_usage(false),
-      ext_texture_storage(false) {
-}
+      ext_texture_storage(false),
+      arb_sync(false) {}
 
 FeatureInfo::Workarounds::Workarounds() :
 #define GPU_OP(type, name) name(false),
@@ -246,6 +246,7 @@ void FeatureInfo::InitializeFeatures() {
   AddExtensionString("GL_CHROMIUM_resize");
   AddExtensionString("GL_CHROMIUM_resource_safe");
   AddExtensionString("GL_CHROMIUM_strict_attribs");
+  AddExtensionString("GL_CHROMIUM_sync_query");
   AddExtensionString("GL_CHROMIUM_texture_mailbox");
   AddExtensionString("GL_EXT_debug_marker");
 
@@ -777,6 +778,9 @@ void FeatureInfo::InitializeFeatures() {
     AddExtensionString("GL_EXT_discard_framebuffer");
     feature_flags_.ext_discard_framebuffer = true;
   }
+
+  if (is_es3 || extensions.Contains("GL_ARB_sync"))
+    feature_flags_.arb_sync = true;

[no sievers, 2014/04/15 18:41:15]

I missed that es3 has this.
We should update gl_fence.cc to use this on es3 (also |ui_gl_fence_works|
above).

 }
 
 void FeatureInfo::AddExtensionString(const std::string& str) {