Add wallpaper api tests

Add wallpaper api tests

This CL add the following tests:
1. test chrome.setWallpaper can set ChromeOS wallpaper from jpg or png formatted arraybuffer.
2. test chrome.setWallpaper can set ChromeOS wallpaper from a valid url that point to a jpg or png image.
3. test an invalide URL wont set wallpaper
4. test a new wallpaper request will cancel previous unfinished request


BUG=176183
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=251087

[bshe, 2014-02-06 00:41:11]

Hi Mike.

Do you mind to take a look at this CL? wallpaper API has been in dev channel for
a while. This CL adds some API tests for it. I am hoping to move it to stable
channel in this milestone if possible.

Thanks!

Biao

[bshe, 2014-02-12 21:22:05]

On 2014/02/06 00:41:11, bshe wrote:
> Hi Mike.
> 
> Do you mind to take a look at this CL? wallpaper API has been in dev channel
for
> a while. This CL adds some API tests for it. I am hoping to move it to stable
> channel in this milestone if possible.
> 
> Thanks!
> 
> Biao

friendly ping? thanks

[miket_OOO, 2014-02-12 22:22:38]

On 2014/02/12 21:22:05, bshe wrote:
> On 2014/02/06 00:41:11, bshe wrote:
> > Hi Mike.
> > 
> > Do you mind to take a look at this CL? wallpaper API has been in dev channel
> for
> > a while. This CL adds some API tests for it. I am hoping to move it to
stable
> > channel in this milestone if possible.
> > 
> > Thanks!
> > 
> > Biao
> 
> friendly ping? thanks

Sorry about that! Not sure how I missed this. LGTM.

[bshe, 2014-02-13 15:34:50]

The CQ bit was checked by bshe@chromium.org

[commit-bot: I haz the power, 2014-02-13 15:36:45]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/bshe@chromium.org/153093010/140001

[commit-bot: I haz the power, 2014-02-13 18:27:52]

Change committed as 251087