IWYU in ash/desktop_background/user_wallpaper_delegate.h

BUG=82098
TBR=pkotwicz@chromium.org (for login_display_host_impl.cc)

Review URL: https://codereview.chromium.org/196633004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@256633 0039d316-1c4b-4281-b951-d872f2087c98
Show dialog as separate post task.
Dialog runs nested loop and can destroy data necessary for caller. 

BUG=350537

Review URL: https://codereview.chromium.org/194383002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@256634 0039d316-1c4b-4281-b951-d872f2087c98
Adding fading effect for paint rectangles in HUD layer.

Review URL: https://codereview.chromium.org/187343007

Review URL: https://codereview.chromium.org/187343007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@256635 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 256635