Add IPCs for ash display shortcuts.

services/ui/public/interfaces/display/display_controller.mojom

 // 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.
 
 module display.mojom;
 
 import "ui/gfx/geometry/mojo/geometry.mojom";
 
 // An interface for clients that are allowed to make changes to the display 
 // state.
 interface DisplayController {
 
+  // =========================== Keyboard Shortcuts ===========================
+
+  // Rotate the current display by 90° CW. The current display is the display
+  // closest to the mouse cursor.
+  RotateCurrentDisplay();

[James Cook, 2016/12/01 16:38:50]

How about calling this RotateCurrentDisplayCW() so it self-documents the
direction?

[kylechar, 2016/12/01 18:43:31]

Done.

+
   // Swap the primary display and the next display.
   SwapPrimaryDisplay();
 
+  // Toggles between mirroring and extended mode.
+  ToggleMirrorMode();
+
+  // Increase zoom on internal display.
+  ZoomInternalDisplayUp();

[James Cook, 2016/12/01 16:38:50]

As a non-graphics person I'm not sure if ZoomUp means making things look bigger
or smaller. Maybe ZoomInInternalDisplay? IncreaseInternalDisplayZoom for
symmetry with ResetInternalDisplayZoom?

[kylechar, 2016/12/01 18:43:31]

I agree, up/down doesn't make much sense. Changed.

+
+  // Decrease zoom on internal display.
+  ZoomInternalDisplayDown();
+
+  // Reset zoom on internal display to default level.
+  ResetInternalDisplayZoom();
+
+  // ========================= Configuration Changes ==========================
+
   // Sets the display work area with the provided insets. The display size is
   // included to ensure that the insets are for the current display size.
   SetDisplayWorkArea(int64 display_id, 
                      gfx.mojom.Size size,
                      gfx.mojom.Insets insets);
 
   // TODO(kylechar): This interface will need to be expanded to provide
   // additional functionality for the display settings page and other ash
   // keyboard accelerators.
 };