gpu: Some cleanups.

ash/gpu_support.h

Index: ash/gpu_support.h
diff --git a/ash/gpu_support.h b/ash/gpu_support.h
index 9acda9cb0b30dcf4a42961e7c5c6fd250fbe29b9..ce371e49a85a01943f7d868cee6a681b1b2d19b5 100644
--- a/ash/gpu_support.h
+++ b/ash/gpu_support.h
@@ -17,15 +17,9 @@ namespace ash {
 // configurations that permit a dependency on content.
 class ASH_EXPORT GPUSupport {
  public:
-  typedef base::Callback<void(const std::list<base::ProcessHandle>&)>
-      GetGpuProcessHandlesCallback;
-
   virtual ~GPUSupport() {}
 
   virtual bool IsPanelFittingDisabled() const = 0;
-
-  virtual void GetGpuProcessHandles(
-      const GetGpuProcessHandlesCallback& callback) const = 0;
 };
 
 }  // namespace ash