Merge Prevent DisplayPreferences from saving incorrect rotations.

Merge Prevent DisplayPreferences from saving incorrect rotations.
Refactor DisplayInfo::rotation_ to track different sources of rotations

Currently DisplayInfo only tracks the active rotation for the given display.
DisplayPreferences however saves a user rotation, as well as an accelerometer
rotation. DisplayController::Observer::OnDisplayConfigurationChanged triggers
the saving of display preferences.

This has been leading to active accelerometer rotations being saved as user
preferences, and being re-applied upon reboot.

This change refactors DisplayInfo to track one rotation per source of rotation
changes. DisplayPreferences has been updated to save based on these states.

TEST=DisplayPreferencesTest.DontSaveMaximizeModeControllerRotations, also ran
ash_unittests, and unit_tests
BUG=chrome-os-partner:37555, 469752, 466861
TBR=oshima@chromium.org, mukai@chromium.org, kalman@chromium.org
NOTRY=true
NOPRESUBMIT=true

Review URL: https://codereview.chromium.org/1071353003

Cr-Commit-Position: refs/heads/master@{#326614}
(cherry picked from commit d01de7f9b271d29dc1fe9126357a36c5563f0ff0)

[jonross, 2015-04-28 14:04:24]

The CQ bit was checked by jonross@chromium.org

[commit-bot: I haz the power, 2015-04-28 14:04:29]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1107383002/1

[commit-bot: I haz the power, 2015-04-28 14:06:00]

Committed patchset #1 (id:1)

[jonross, 2015-04-28 15:04:23]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.chromium.org/1108343002/ by jonross@chromium.org.

The reason for reverting is: Merge issue broke cros build

https://uberchromegw.corp.google.com/i/chrome/builders/cros%20beta/builds/8333.