Add ability to get raw data and range requests to to PrivetURLFetcher

Add ability to read data without parsing it as JSON to PrivetURLFetcher. In
addition, add the ability to send range requests.

BUG=332182

Review URL: https://codereview.chromium.org/156143002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@250846 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 250846
Cast: Added missing DCHECKs to ThreadChecker calls and minor cleanup.

Also included in this CL are:
- Removed task_runner in constructor of RawEventSubscriber impls
- Minor fixes in unittests

Review URL: https://codereview.chromium.org/145873007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@250847 0039d316-1c4b-4281-b951-d872f2087c98
Revert of cc: Disable "activate to low res" optimization (https://codereview.chromium.org/150403007/)

Reason for revert:
Reverting temporary patch merged to m33.

Original issue's description:
> cc: Disable "activate to low res" optimization
> 
> This optimization is broken on m33 and causes flashing to tabs.  Turning
> off the optimization fixes the problem.  This is an intentionally small
> patch meant for merging to m33 and then immediately reverting on trunk.
> 
> BUG=335289
> 
> Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=250332

TBR=danakj@chromium.org
BUG=335289

Review URL: https://codereview.chromium.org/161023002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@250848 0039d316-1c4b-4281-b951-d872f2087c98
sync: Move migration signal out of snapshot

A sync data migration request is signalled by the server during a normal
GetUpdates or Commit request.  The signal is then forwarded to the UI thread,
which actually performs the migration.

Traditionally, the signal has been sent through the SyncSessionSnapshot, which
is delivered to the UI thread at the end of the current sync cycle.  This CL
introduces new code to pass the signal through the SyncSession::Delegate and
SyncManagerObserverInterfaces.

This CL should not change the syncer's behavior.

BUG=339984

Review URL: https://codereview.chromium.org/158953004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@250849 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 250849