Clear testing callbacks in AppBackgrounPageNaclTest reentrantly.

Addresses a flaky ASAN failure where I believe callbacks from ImpulseCallbackCounter with an unretained reference were being held too long by ProcessManager.

This clears the callbacks immediately when the impulse count is reached, and does not call the quit closure repeatedly.

BUG=332440

Review URL: https://codereview.chromium.org/129243003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@244247 0039d316-1c4b-4281-b951-d872f2087c98
Adding a menu item to take a screenshot under "More Tools" submenu in the Wrench menu. 

The behavior is equivalent to taking the screenshot via VKEY_PRINT keyboard shortcut.

BUG=196658

Review URL: https://codereview.chromium.org/132233003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@244248 0039d316-1c4b-4281-b951-d872f2087c98
Moved url_handlers from dev to stable

BUG=333092

Review URL: https://codereview.chromium.org/132533003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@244249 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 244249
Unrevert 244233 "Add support for using expressions as enum values."

First time broke the build with a non-ASCII character in a comment.

BUG=320090
TBR=darin@chromium.org

Review URL: https://codereview.chromium.org/131833004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@244250 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 244250