[Search] Adding a URLDataSource for search feature

[Search] Adding a URLDataSource for search feature

This implements the first-run flow for the contextual search feature. Resources are being committed in a different CL.

BUG=374932
TEST=going to chrome://contextual-search/

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=281818

[Mathieu, 2014-07-07 19:48:18]

Hi Jered, 

Can you have a look? Thanks

[Jered, 2014-07-07 20:19:39]

On 2014/07/07 19:48:18, Mathieu Perreault wrote:
> Hi Jered, 
> 
> Can you have a look? Thanks

lgtm assuming this builds and works fine with the missing parts included (e.g.
the hostname constant)

[Jered, 2014-07-07 20:20:32]

On 2014/07/07 20:19:39, Jered wrote:
> On 2014/07/07 19:48:18, Mathieu Perreault wrote:
> > Hi Jered, 
> > 
> > Can you have a look? Thanks
> 
> lgtm assuming this builds and works fine with the missing parts included (e.g.
> the hostname constant)

(You might consider using the chrome-search:// scheme if you want instant
process
assignment/isolation semantics. I'm assuming you don't, and so a normal
chrome://
url is ok.)

[Mathieu, 2014-07-08 13:51:55]

The CQ bit was checked by mathp@chromium.org

[commit-bot: I haz the power, 2014-07-08 13:52:35]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/mathp@chromium.org/375593004/1

[commit-bot: I haz the power, 2014-07-08 20:25:22]

Change committed as 281818