android: Fix ContentViewCore and RenderWidgetHostViewAndroid lifetime issue

https://codereview.chromium.org/26753005/ might have introduced crashes that
trace to SetContentViewCore.  That previous patch assumed that ContentViewCore
(CVC) always outlives its associated RenderWidgetHostView.  In this patch, we
are trying to ensure that the RWHVA pointer to CVC is nulled when CVC is
destroyed.

Note the following:
- WebContents owns ContentViewCore and WebContentsView.
- CVC and WebContentsView are implicitly destroyed (no direct call to clean-up
code).  So ContentViewCore cannot refer to WebContents or WebContentsView in
its destructor.

Therefore, we use the observer of when WebContents is destroyed to start the
clean up on CVC.


BUG=335165, 324341

Review URL: https://codereview.chromium.org/133073012

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@247878 0039d316-1c4b-4281-b951-d872f2087c98
QuotaManager: Don't fire callback if it's null

BUG=n/a
R=nhiroki@chromium.org

Review URL: https://codereview.chromium.org/147143005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@247879 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 247878
Mojo: Remove '*' from the list of unary operators in mojom expressions.

R=mpcomplete@chromium.org

Review URL: https://codereview.chromium.org/149703003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@247880 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 247880