Polish the keybinding implementation a bit.

- Make it require manifest version 2.
- Change 'key' to 'suggested_key', allow it to be a string or a dictionary with platforms and/or 'default' listed.
- Converted browser_action in manifest to _execute_browser_action, since that keyword is reserved (same for page action).
- Remove normalization of suggested_key (stop supporting Ctrl - foo, now only Ctrl+foo and make it case sensitive).
- Added methods to fetch just browser actions/just page actions (or all others), which is what you'd commonly want.

BUG=27702
TEST=Covered by automated tests.
Review URL: https://chromiumcodereview.appspot.com/9812008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@130114 0039d316-1c4b-4281-b951-d872f2087c98
16 files changed