Refactor DisplayInfo/Display - 3rd try

This is a first step to fix overscan issue and implement
screen rotation.

* remove bounds_in_pixel from gfx::Display
* promote DisplayInfo to separate class/file
* All display information is now generated in display_change_observer_x11.cc.
  almost no X11 depenency in display_manager.cc
 (I'll move FindInternalDisplayID out from display_manager.cc once https://codereview.chromium.org/12217120/ is landed)

  This makes testing more consistent with real environment.

* Add DisplayManager::ClearCustomOverscanInsets so that
  you can reset the insets to default value.
* Removed obsolete AshTestBase::ChangeDisplayConfig

BUG=174721,119268
TEST=covered by test

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=185178

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=185230

Review URL: https://chromiumcodereview.appspot.com/12218045

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@185367 0039d316-1c4b-4281-b951-d872f2087c98
23 files changed