Inject GPUDataManager support into ash to abstract a content dependency.

ash/shell.h

Index: ash/shell.h
diff --git a/ash/shell.h b/ash/shell.h
index a452cd53ea473bf7e5d54b8df26ecba669c4cc16..ff58e66372b4a004ad81c46deec72f43d585fe14 100644
--- a/ash/shell.h
+++ b/ash/shell.h
@@ -83,6 +83,7 @@ class CapsLockDelegate;
 class DesktopBackgroundController;
 class DisplayController;
 class FirstRunHelper;
+class GPUSupport;
 class HighContrastController;
 class LockStateController;
 class MagnificationController;
@@ -535,6 +536,9 @@ class ASH_EXPORT Shell
   }
 #endif  // defined(OS_CHROMEOS)
 
+  GPUSupport* gpu_support() { return gpu_support_.get(); }
+  void SetGPUSupport(scoped_ptr<GPUSupport> gpu_support);
+
  private:
   FRIEND_TEST_ALL_PREFIXES(ExtendedDesktopTest, TestCursor);
   FRIEND_TEST_ALL_PREFIXES(WindowManagerTest, MouseEventCursors);
@@ -707,6 +711,9 @@ class ASH_EXPORT Shell
 
   bool is_touch_hud_projection_enabled_;
 
+  // Injected content::GPUDataManager support.
+  scoped_ptr<GPUSupport> gpu_support_;
+
   DISALLOW_COPY_AND_ASSIGN(Shell);
 };