allow overriding default_font_cache_limit

Android uses a 1M default skia glyph cache, but all other builds that
use skia default to 20M.  This patch makes the value configurable so non-android builds can choose an optimal value.

Review URL: https://codereview.chromium.org/41173002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@230999 0039d316-1c4b-4281-b951-d872f2087c98
Fix crash when attempting to grant a page when there have been no navigation entries.
This occurs if you click on the browser action for an extension that supports grants really quickly before the tab loads.

BUG=311375

Review URL: https://codereview.chromium.org/42043002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@231000 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 231000