Prevent DisplayPreferences from saving incorrect rotations.

ui/gfx/display.h

 // Copyright (c) 2012 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 UI_GFX_DISPLAY_H_
 #define UI_GFX_DISPLAY_H_
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "ui/gfx/geometry/rect.h"
@@ skipping 12 matching lines @@
 class GFX_EXPORT Display {
  public:
   // Screen Rotation in clock-wise degrees.
   enum Rotation {
     ROTATE_0 = 0,
     ROTATE_90,
     ROTATE_180,
     ROTATE_270,
   };
 
+  // The cause of a change in display rotation.

[tdanderson, 2015/04/13 22:44:46]

Nit: For the ease of someone reading this for the first time, consider giving a
bit more context in the comment regarding what each of these mean.

[jonross, 2015/04/15 17:43:12]

Done.

+  enum RotationSource {
+    ROTATION_SOURCE_ACCELEROMETER = 0,
+    ROTATION_SOURCE_ACTIVE,
+    ROTATION_SOURCE_USER,
+  };
+
   // Touch support for the display.
   enum TouchSupport {
     TOUCH_SUPPORT_UNKNOWN,
     TOUCH_SUPPORT_AVAILABLE,
     TOUCH_SUPPORT_UNAVAILABLE,
   };
 
   // Creates a display with kInvalidDisplayID as default.
   Display();
   explicit Display(int64 id);
@@ skipping 86 matching lines @@
   Rect bounds_;
   Rect work_area_;
   float device_scale_factor_;
   Rotation rotation_;
   TouchSupport touch_support_;
 };
 
 }  // namespace gfx
 
 #endif  // UI_GFX_DISPLAY_H_