GitLab

- Create ShellAcceleratorController that manages global keyboard accelerators and also processes several accelerators as a target.
- Create ShellAcceleratorFilter, which is used by DesktopEventFilter to handle accelerators.
- Add a function to Shell for accessing ShellAcceleratorController.

BUG=97255
TEST=Manual


Review URL: http://codereview.chromium.org/8465021

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@110637 0039d316-1c4b-4281-b951-d872f2087c98