[Sync] Add interface and backend impl for typed URL syncable service

[Sync] Add interface and backend impl for typed URL syncable service

The typed URL sync datatype is being transitioned to the syncable service API, 
and this patch introduces the new interface the typed url sync code will use 
to communicate with sync as well as the HistoryBackend which implements the 
datatype. 

This patch implements logic for syncing typed url changes originating from 
the history backend to the sync server, through the syncable service API. 

Original patch by mgist1@chromium.org.
Review at https://codereview.chromium.org/12703036/

BUG=77819
TBR=brettw@chromium.org, atwilson@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=198789

[Nicolas Zea, 2013-05-06 19:23:46]

+TBR Drew and Brett. This just rebases addresses the final nits from Brett.
Landing via commitbot

[commit-bot: I haz the power, 2013-05-06 19:24:19]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/zea@chromium.org/14615010/14

[commit-bot: I haz the power, 2013-05-06 19:58:16]

Sorry for I got bad news for ya.
Compile failed with a clobber build on android_clang_dbg.
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=android_cl...
Your code is likely broken or HEAD is junk. Please ensure your
code is not broken then alert the build sheriffs.
Look at the try server FAQ for more details.

[commit-bot: I haz the power, 2013-05-06 20:59:48]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/zea@chromium.org/14615010/16001

[commit-bot: I haz the power, 2013-05-06 21:49:44]

Sorry for I got bad news for ya.
Compile failed with a clobber build on android_clang_dbg.
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=android_cl...
Your code is likely broken or HEAD is junk. Please ensure your
code is not broken then alert the build sheriffs.
Look at the try server FAQ for more details.

[commit-bot: I haz the power, 2013-05-06 21:54:01]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/zea@chromium.org/14615010/30001

[commit-bot: I haz the power, 2013-05-06 23:04:56]

Retried try job too often on linux_rel for step(s) interactive_ui_tests
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=linux_rel&...

[commit-bot: I haz the power, 2013-05-07 17:20:37]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/zea@chromium.org/14615010/30001

[commit-bot: I haz the power, 2013-05-07 17:56:07]

Retried try job too often on linux_rel for step(s) interactive_ui_tests
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=linux_rel&...

[commit-bot: I haz the power, 2013-05-07 20:01:04]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/zea@chromium.org/14615010/30001

[commit-bot: I haz the power, 2013-05-07 20:28:42]

Retried try job too often on linux_rel for step(s) interactive_ui_tests
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=linux_rel&...

[Nicolas Zea, 2013-05-07 20:35:51]

Committed patchset #4 manually as r198789 (presubmit successful).