Revert 241681 "Let test_isolation_mode default to check on mac."

Still not working on the branded builders, lots of .isolate files still
hardcode "chromium framework" (see http://crbug.com/324911)

> Let test_isolation_mode default to check on mac.
> 
> It was set to noop in https://chromiumcodereview.appspot.com/14055005 due to
> issues with xcode. Now that xcode is no longer used, it can be set to check
> again.
> 
> BUG=none
> 
> Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=238025
> 
> R=maruel@chromium.org
> 
> Review URL: https://codereview.chromium.org/92303002

TBR=thakis@chromium.org

Review URL: https://codereview.chromium.org/110423005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@241705 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 241705
Optimize ExtensionAPI::IsAnyFeatureAvailableToContext from O(#features) to O(#children + log #features).

This also replaces O(N) string allocations with 1 and moves the top-level
feature check to the top of the function to provide a quick exit when the
context has full access.

And it adds an IsAvailable() overload taking a Feature to avoid the string
copies in GetFeatureDependency().

BUG=305000

Review URL: https://codereview.chromium.org/107473004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@241706 0039d316-1c4b-4281-b951-d872f2087c98
Sync PRESUBMIT.py with CQ's projects.py.

This is a reland of https://codereview.chromium.org/58803002 which was reverted in https://codereview.chromium.org/64473002. It has been updated to reflect the latest projects.py changes.

BUG=278554
R=maruel@chromium.org

Review URL: https://codereview.chromium.org/116673003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@241707 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 241707