EmbeddedWorker, browser side code

Adding two new classes, EmbeddedWorkerRegistry and EmbeddedWorkerInstance.
Technically they can be implemented within ServiceWorkerContextCore and
ServiceWorkerVersion, but here I wrote them in separate classes for logical
separation.

* EmbeddedWorkerRegistry
-- Hangs off the ServiceWorkerContextCore
-- Acts as a stub between MessageFilter and each EmbeddedWorkerInstance
-- Sends/receives messages to/from each EmbeddedWorker in child process
-- Mostly talks only with MessageFilter and EmbeddedWorkerInstance

* EmbeddedWorkerInstance
-- ServiceWorkerVersion will own it (1:1 relation)
-- Provides an interface to interact (Start/Stop/Execute) with an EmbeddedWorker

BUG=313530
TBR=jochen

Review URL: https://codereview.chromium.org/85023003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@240030 0039d316-1c4b-4281-b951-d872f2087c98
Rebuild the cache when a notification is marked as shown or displayed.

These operations update the unread count.

BUG=327055
R=dewittj@chromium.org
TEST=none

Review URL: https://codereview.chromium.org/98853010

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@240031 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 240031
SyncFS: Remove unused code from DriveFileSyncService and DriveMetadataStore


BUG=n/a
TEST=n/a
NOTRY=true

Review URL: https://codereview.chromium.org/103063003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@240032 0039d316-1c4b-4281-b951-d872f2087c98
SyncFS: Clean up test utils


BUG=n/a
TEST=n/a
NOTRY=true

Review URL: https://codereview.chromium.org/103913006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@240033 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 240033