Support hiding bookmark star under Cocoa

This is the Cocoa UI implementation to allow extensions to hide the
bookmark star for the purpose of providing alternate UI for creating
bookmarks.

See http://crrev.com/240286 for the initial extension + Views
implementation. The corresponding API proposal document is at:
https://docs.google.com/a/chromium.org/document/d/17YldHwrDBZ2L5lXWo7eDff_oZIrwNF-8Uk2fPLHU4po/edit


BUG=311282

Review URL: https://codereview.chromium.org/110413003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@240768 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 240768
Add a flag to force disable libstdc++ debug mode.

BUG=328249, 65151
R=kbr@chromium.org

Review URL: https://codereview.chromium.org/102903005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@240769 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 240769
cros: Remove default pinned apps trial.

- Remove the trial code;
- Clean up trial local state value;
- Deprecate UMA;

BUG=234415

Review URL: https://codereview.chromium.org/99763005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@240770 0039d316-1c4b-4281-b951-d872f2087c98
Adds chrome://flags for two omnibox experiments.

BUG=304859, 315944

Review URL: https://codereview.chromium.org/103883006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@240771 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 240771