ash/chromeos: Add shift-alt-p shortcut to open palette.

ash/common/palette_delegate.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef ASH_COMMON_PALETTE_DELEGATE_H_
 #define ASH_COMMON_PALETTE_DELEGATE_H_
 
 #include "ash/ash_export.h"
 #include "base/callback.h"
 #include "base/callback_list.h"
@@ skipping 29 matching lines @@
   virtual void SetPartialMagnifierState(bool enabled) = 0;
 
   // Set callback that is run when a stylus is inserted or removed.
   virtual void SetStylusStateChangedCallback(
       const OnStylusStateChangedCallback& on_stylus_state_changed) = 0;
 
   // Returns true if the palette should be automatically opened on an eject
   // event.
   virtual bool ShouldAutoOpenPalette() = 0;
 
+  // Returns true if the palette should be displayed. This is the one-shot
+  // equivalent to AddPaletteEnableListener.
+  virtual bool ShouldShowPalette() = 0;
+
   // Take a screenshot of the entire window.
   virtual void TakeScreenshot() = 0;
 
   // Take a screenshot of a user-selected region.
   virtual void TakePartialScreenshot() = 0;
 
  private:
   DISALLOW_ASSIGN(PaletteDelegate);
 };
 
 }  // namespace ash
 
 #endif  // ASH_COMMON_PALETTE_DELEGATE_H_