Support png wallpapers

Support png wallpapers

We use a weaker (from security perspective) image decode here
in order to support png wallpapers. The weaker image decoder will
only used after user logged in. So if it somehow exploited, the
damage stays in one user's profile. (Actually, we use image decoder
that webkit use. So it is as safe/dangeous as user open the png
wallpaper in a browser window)

After decoded the png wallpaper, we will reencode it to jpeg. And 
thereafter, a robust jpeg decoder is used to decode the saved
jpegs to guarantee we can safely display wallpaper pre login stage. 


BUG=237416
TEST=
1. have a png image ready
2. open wallpaper picker, navigate to custom tab
3. change wallpaper to the png file
expected: the png file should set as wallpaper

4. logout
5. verify the wallpaper persist

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=206852

[bshe, 2013-06-11 22:16:21]

This CL enables users use PNG files as their wallpapers. All wallpapers will be
re-encoded to jpge when saved to chromeos (for security reasons).

+miket: could you please take a look at everything related to extension?

+nkostylev: could you please take a look at wallpaper related files?

Thanks!

https://codereview.chromium.org/16634016/diff/22001/chrome/test/data/extensio...
File chrome/test/data/extensions/api_test/wallpaper_manager/test.js (left):

https://codereview.chromium.org/16634016/diff/22001/chrome/test/data/extensio...
chrome/test/data/extensions/api_test/wallpaper_manager/test.js:65: function
getCustomWallpaperThumbnail() {
getOfflineWallpaperList is no longer needed for custom wallpaper. So I removed
the test. A follow-up CL will change the getOfflineWallpaperList api to be more
simple.

[Nikita (slow), 2013-06-13 13:03:32]

lgtm

https://codereview.chromium.org/16634016/diff/22001/chrome/browser/chromeos/e...
File chrome/browser/chromeos/extensions/wallpaper_private_api.cc (right):

https://codereview.chromium.org/16634016/diff/22001/chrome/browser/chromeos/e...
chrome/browser/chromeos/extensions/wallpaper_private_api.cc:239: // This
function can only be called after user login. It is fine to use
Please place CHECK here that like

CHECK(chromeos::LoginState::Get()->GetLoggedInState() !=
chromeos::LoginState::LOGGED_IN_USER_NONE)

https://codereview.chromium.org/16634016/diff/22001/chrome/browser/resources/...
File chrome/browser/resources/chromeos/wallpaper_manager/main.html (right):

https://codereview.chromium.org/16634016/diff/22001/chrome/browser/resources/...
chrome/browser/resources/chromeos/wallpaper_manager/main.html:72: <input
id="file-selector" type="file" size="80" accept="image/jpeg, image/png">
nit: 80 chars limit, please move accept attribute next line

[bshe, 2013-06-14 18:12:18]

Done.

miket, could you please take a look at extension related code?

Thanks!

https://codereview.chromium.org/16634016/diff/22001/chrome/browser/chromeos/e...
File chrome/browser/chromeos/extensions/wallpaper_private_api.cc (right):

https://codereview.chromium.org/16634016/diff/22001/chrome/browser/chromeos/e...
chrome/browser/chromeos/extensions/wallpaper_private_api.cc:239: // This
function can only be called after user login. It is fine to use
On 2013/06/13 13:03:33, Nikita Kostylev wrote:
> Please place CHECK here that like
> 
> CHECK(chromeos::LoginState::Get()->GetLoggedInState() !=
> chromeos::LoginState::LOGGED_IN_USER_NONE)

Done.

https://codereview.chromium.org/16634016/diff/22001/chrome/browser/resources/...
File chrome/browser/resources/chromeos/wallpaper_manager/main.html (right):

https://codereview.chromium.org/16634016/diff/22001/chrome/browser/resources/...
chrome/browser/resources/chromeos/wallpaper_manager/main.html:72: <input
id="file-selector" type="file" size="80" accept="image/jpeg, image/png">
On 2013/06/13 13:03:33, Nikita Kostylev wrote:
> nit: 80 chars limit, please move accept attribute next line

Done.

[miket_OOO, 2013-06-14 19:57:03]

LGTM but please update the CL description to briefly mention the safe/unsafe
logged-in/not-logged-in part. It's unexpected otherwise to see that change in
this CL, given the current CL description.

https://codereview.chromium.org/16634016/diff/31001/chrome/browser/chromeos/e...
File chrome/browser/chromeos/extensions/wallpaper_private_api.cc (right):

https://codereview.chromium.org/16634016/diff/31001/chrome/browser/chromeos/e...
chrome/browser/chromeos/extensions/wallpaper_private_api.cc:242: // unsafe image
deocder here. Before user login, a robust jpeg decoder will
spelling

[commit-bot: I haz the power, 2013-06-17 15:50:53]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/bshe@chromium.org/16634016/41001

[commit-bot: I haz the power, 2013-06-17 23:07:27]

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

[commit-bot: I haz the power, 2013-06-17 23:15:10]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/bshe@chromium.org/16634016/41001

[commit-bot: I haz the power, 2013-06-18 00:08:35]

Change committed as 206852