Read compositor VSync information from platform, when possible

chromeos/display/output_configurator.h

Index: chromeos/display/output_configurator.h
diff --git a/chromeos/display/output_configurator.h b/chromeos/display/output_configurator.h
index 8a8b36d49e73bda7112b503965994e9bf139ac14..cd1734b5e6dad73107179df79275c916077e414c 100644
--- a/chromeos/display/output_configurator.h
+++ b/chromeos/display/output_configurator.h
@@ -173,11 +173,12 @@ class CHROMEOS_EXPORT OutputConfigurator
     virtual OutputState GetStateForDisplayIds(
         const std::vector<int64>& display_ids) const = 0;
 
-    // Queries the resolution (|width|x|height|) in pixels
-    // to select output mode for the given display id.
+    // Queries the resolution (|width|x|height|) in pixels and |refresh_rate| in
+    // Hz to select output mode for the given display id.
     virtual bool GetResolutionForDisplayId(int64 display_id,
                                            int* width,
-                                           int* height) const = 0;
+                                           int* height,
+                                           float* refresh_rate) const = 0;

[oshima, 2014/01/27 18:53:22]

Looks like you're not using refresh_rate in output configurator. Do you need
this here?

[sheu, 2014/01/28 21:30:42]

Done.

   };
 
   // Interface for classes that implement software based mirroring.