Fix TabCaptureApiTest.GrantForChromePages flakey failures

In this test we base::Bind DidCopyFromBackingStore into callbacks to be
executed OnSnapshot. If we WebContentsCaptureMachine::Stop before these
callbacks come in, then render_thread_ will be set to NULL, and if
these callbacks end up being executed after this point, but before the
WebContentsCaptureMachine is destroyed, access to to a NULL
render_thread_ will result.

BUG=340475

Review URL: https://codereview.chromium.org/151733003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@248961 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 248961
Fix old_inbox_app in key_silk_pages.

We should swipe on the 'content' element rather than the 'nav-drawer' element.
The latter one spans the entire page, rather than just the drawer. This causes
problems on tablets, e.g. N7, where the drawer only covers about half the page
and the swipe often doesn't actually close it.

BUG=332439

Review URL: https://codereview.chromium.org/151383002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@248962 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 248962
Files.app: Add multiprofile events to fileBrowserPrivate API.

This CL adds onProfileAdded and onWindowVisited events to fileBrowserPrivate
API.

To add the onWindowVisited event, the CL adds observer to MultiUserWindowManager
and lets MultiUserNotificationBlockerChromeOS to use it.

BUG=338603, 339958
TEST=manually

Review URL: https://codereview.chromium.org/137223004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@248963 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 248963