Convert mustash use surface references.

services/ui/ws/platform_display.h

Index: services/ui/ws/platform_display.h
diff --git a/services/ui/ws/platform_display.h b/services/ui/ws/platform_display.h
index 33ad23ecec99670c01907c07cde32c3530953154..46ab18f03c72c1b6c74997d76d0ff6dfb402e95b 100644
--- a/services/ui/ws/platform_display.h
+++ b/services/ui/ws/platform_display.h
@@ -90,6 +90,8 @@ class PlatformDisplay {
 
   virtual bool IsPrimaryDisplay() const = 0;
 
+  virtual FrameGenerator* GetFrameGenerator() = 0;
+
   // Notifies the PlatformDisplay that a connection to the gpu has been
   // established.
   virtual void OnGpuChannelEstablished(
@@ -131,6 +133,7 @@ class DefaultPlatformDisplay : public PlatformDisplay,
   bool IsPrimaryDisplay() const override;
   void OnGpuChannelEstablished(
       scoped_refptr<gpu::GpuChannelHost> gpu_channel) override;
+  FrameGenerator* GetFrameGenerator() override;
 
  private:
   // Update the root_location of located events to be relative to the origin