sync: Deprecate old UniquePosition format

Drop support for legacy UniquePosition encoding.

Some old clients (M28 and M29) only understand the uncompressed and gzip
encodings of UniquePositions.  To maintain compatibility with them,
clients that supported the newer and better custom compression algorithm
(M30 and above) wrote protobufs that contained both the old and new
encodings.

Maintaining backwards compatibility in this way is expensive.  It's not
a big deal for clients that have a reasonable number of bookmarks, but
for the few users that have thousands of them this could be a real
problem.

Since those old clients are now much rarer, it should be safe to no
longer write the extra encoding just for them.  If any of those older
clients do come across protobufs that are newer than what they support,
they will fail to apply the position updates.  In other words, bookmarks
modified on newer clients will have randomly assigned positions on older
clients.  Those older clients will also run over a NOTREACHED(), but I
don't think this will do any harm in practice.

BUG=260394

Review URL: https://codereview.chromium.org/68533007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@235380 0039d316-1c4b-4281-b951-d872f2087c98
[SyncFS] Delete local file on rename and reorganize.

 * Handle remote rename and reorganize by local file deletion.
 * Delete tracker on rename and reorganize completion.

BUG=240165
NOTRY=true

Review URL: https://codereview.chromium.org/71233003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@235381 0039d316-1c4b-4281-b951-d872f2087c98
Use JsonDoubleQuote to output trace string

The original code to output trace string was incomplete that control
characters may break the trace file. Use JsonDoubleQuote which can
handle the case.

BUG=317874
TEST=TraceEventTestFixture.DataCaptured etc. (existing)

Review URL: https://codereview.chromium.org/71853002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@235382 0039d316-1c4b-4281-b951-d872f2087c98
[Telemetry] Improve instructions for checking out archives.

BUG=271587

The cq is borked :(
NOTRY=True

Review URL: https://codereview.chromium.org/72183002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@235383 0039d316-1c4b-4281-b951-d872f2087c98
Disable NaClExtensionTest.NonWebStoreExtension

BUG=319892

Review URL: https://codereview.chromium.org/74213003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@235391 0039d316-1c4b-4281-b951-d872f2087c98
Linux: respect use_gconf in Aura

BUG=none
R=erg@chromium.org

Review URL: https://codereview.chromium.org/73083004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@235392 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 235392