Revert 142427 - Cleaning Up Extensions When Local Content Removed

Revert 142427 - Cleaning Up Extensions When Local Content Removed

This fixes an issue where removing an extension's local content, e.g. deleting
the user-data-dir/Default/Extensions/<id> directory, would result in a broken
extension. Chrome will now uninstall/remove any extensions where the path to
the extension cannot be resolved.

BUG=31910
TEST=ExtensionServiceTest.CleanupInternalExtensionsMissingLocalContent;
ExtensionServiceTest.CleanupUnpackedExtensionsMissingLocalContent;
test by hand by loading an extension, deleting the local directory, and
restarting chrome


Review URL: https://chromiumcodereview.appspot.com/10541126

TBR=rdevlin.cronin@chromium.org
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=143047