Prevent DisplayPreferences from saving incorrect rotations.

ui/gfx/display.h

Index: ui/gfx/display.h
diff --git a/ui/gfx/display.h b/ui/gfx/display.h
index 6f29d424a8dc2687ae972215bbbe5e3f15db833c..adc11ad3163371eca434372c6bb4462238bbff3f 100644
--- a/ui/gfx/display.h
+++ b/ui/gfx/display.h
@@ -30,6 +30,18 @@ class GFX_EXPORT Display {
     ROTATE_270,
   };
 
+  // The display rotation can have multiple causes for change. A user can set a
+  // preference. On devices with accelerometers, they can change the rotation.
+  // RotationSource allows for the tracking of a Rotation per source of the
+  // change. ROTATION_SOURCE_ACTIVE is the current rotation of the display.
+  // Rotation changes not due to an accelerometer, nor the user, are to use this
+  // source directly.
+  enum RotationSource {
+    ROTATION_SOURCE_ACCELEROMETER = 0,
+    ROTATION_SOURCE_ACTIVE,
+    ROTATION_SOURCE_USER,
+  };
+
   // Touch support for the display.
   enum TouchSupport {
     TOUCH_SUPPORT_UNKNOWN,