Revert of Keep track of which attachments are referenced by which sync entries.

Revert of Keep track of which attachments are referenced by which sync entries. (https://codereview.chromium.org/247983002/)

Reason for revert:
Looks like this may have introduced a memory leak:

http://build.chromium.org/p/chromium.memory.fyi/builders/Linux%20Tests%20%28valgrind%29%282%29/builds/37232

Reverting.  Will investigate and reland when appropriate.

Original issue's description:
> Keep track of which attachments are referenced by which sync entries.
> 
> PutAttachmentMetadata on MutableEntry now notifies the Directory when
> the attachments associated with an entry change.
> 
> Give Directory::InitializeIndices a ScopedKernelLock to be consistent
> and make it easier to ensure we are locking when we need to.
> 
> GenericChangeProcess passes new attachments to AttachmentService for
> storage and upload.
> 
> Add an output parameter to GenericChangeProcessor's HandleActionAdd and
> HandleActionUpdate methods so they can keep track of potentially new
> attachments and pass them to AttachmentService for storage/upload.
> 
> Convert AttachmentService's OnSyncDataAdd to StoreAttachments.
> 
> Implement HasAttachmentNotOnServer.
> 
> BUG=348625, 353303, 354530, 356266
> 
> Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=267617

TBR=pavely@chromium.org,tim@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=348625, 353303, 354530, 356266
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=267649

[maniscalco, 2014-05-01 21:58:53]

Created Revert of Keep track of which attachments are referenced by which sync
entries.

[commit-bot: I haz the power, 2014-05-01 21:59:47]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/maniscalco@chromium.org/265853004/1

[commit-bot: I haz the power, 2014-05-01 21:59:48]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-05-01 21:59:48]

No LGTM from a valid reviewer yet. Only full committers are accepted.
Even if an LGTM may have been provided, it was from a non-committer or
a provisional committer, _not_ a full super star committer.
See http://www.chromium.org/getting-involved/become-a-committer
Note that this has nothing to do with OWNERS files.

[Lei Zhang, 2014-05-01 22:00:49]

The CQ bit was checked by thestig@chromium.org

[commit-bot: I haz the power, 2014-05-01 22:04:35]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/maniscalco@chromium.org/265853004/1

[commit-bot: I haz the power, 2014-05-01 22:04:41]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-05-01 22:04:41]

No LGTM from a valid reviewer yet. Only full committers are accepted.
Even if an LGTM may have been provided, it was from a non-committer or
a provisional committer, _not_ a full super star committer.
See http://www.chromium.org/getting-involved/become-a-committer
Note that this has nothing to do with OWNERS files.

[Lei Zhang, 2014-05-01 22:07:02]

and lgtm

[Lei Zhang, 2014-05-01 22:07:05]

The CQ bit was checked by thestig@chromium.org

[commit-bot: I haz the power, 2014-05-01 22:07:41]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/maniscalco@chromium.org/265853004/1

[commit-bot: I haz the power, 2014-05-01 22:10:42]

Change committed as 267649