mash: Make the power button shut the system down.

ash/common/wm_shell.h

Index: ash/common/wm_shell.h
diff --git a/ash/common/wm_shell.h b/ash/common/wm_shell.h
index f13fb91ff488616fd40aa8f3164c335ba39c8765..d6bfae07b5011b418e2f0cc2029422c55e028bc4 100644
--- a/ash/common/wm_shell.h
+++ b/ash/common/wm_shell.h
@@ -430,12 +430,6 @@ class ASH_EXPORT WmShell : public SessionStateObserver,
   void AddLockStateObserver(LockStateObserver* observer);
   void RemoveLockStateObserver(LockStateObserver* observer);
 
-  // Displays the shutdown animation and requests a system shutdown or system
-  // restart depending on the the state of the |RebootOnShutdown| device policy.
-  // TODO(mash): Remove this method and call LockStateController directly when
-  // it is available to code in ash/common.
-  virtual void RequestShutdown() = 0;
-
   void SetShelfDelegateForTesting(std::unique_ptr<ShelfDelegate> test_delegate);
   void SetPaletteDelegateForTesting(
       std::unique_ptr<PaletteDelegate> palette_delegate);