Fix initialization of a11y on-scrren keyboard when initializing profile.

BUG=339815

Review URL: https://codereview.chromium.org/151543002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@248253 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 248253
Disable DeclarativeContentApiTest.AddExtensionMatchingExistingTabWithDeadFrames test.

This test is flaky on several bots. See bug.

TBR=jyasskin@chromium.org
BUG=339896

Review URL: https://codereview.chromium.org/151613005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@248254 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 248254