Display fallback icons in case of errors in the mosaic view.

Previously, a black rectangle was shown isntead of the fallback icon. This patch fixes this issue.

TEST=Tested manually. Partly covered by browser_tests.
BUG=303978
R=yoshiki@chromium.org

Review URL: https://codereview.chromium.org/25646009

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@227398 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 227398
Drop wrong NOTREACHED() in AudioRendererHost::DoCompleteCreation().

The renderer process may die before the browser can respond for a number of
reasons (crash, in-flight kill, etc).

BUG=301571
TEST=none
R=dalecurtis@chromium.org

Review URL: https://codereview.chromium.org/26165002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@227399 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 227399