Fixes crashes wrt to the maximize button when:
- A user hovers the minimize button with the mouse then taps the snap left / snap right button
- When the MaximizeBubbleFrameState computed by GetMaximizeBubbleFrameState() changes while the maximize button help bubble is visible due to the work area bounds changing (See comment #6 in bug)

BUG=342867
TEST=FrameMaximizeButtonTest.MaximizeBubbleMouseHoverAndTouch

Review URL: https://codereview.chromium.org/166543004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@251589 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 251589