Remove ui::GetImageScale

Remove ui::GetImageScale
* and replace it with ui::GetScaleForScaleFactor
* Minor simplification of if blocks in FaviconService

BUG=372212
R=ananta@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=276421

[ananta, 2014-06-10 21:57:02]

lgtm

[oshima, 2014-06-10 21:58:30]

sky -> owners

[sky, 2014-06-10 22:31:57]

LGTM

[oshima, 2014-06-10 22:45:41]

The CQ bit was checked by oshima@chromium.org

[commit-bot: I haz the power, 2014-06-10 22:47:30]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/oshima@chromium.org/326143002/20001

[commit-bot: I haz the power, 2014-06-11 03:57:26]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  mac_chromium_compile_dbg on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/mac_chromium_compile_...)
  mac_chromium_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/mac_chromium_rel/buil...)
  win_chromium_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/win_chromium_rel/buil...)
  mac_gpu on tryserver.chromium.gpu
(http://build.chromium.org/p/tryserver.chromium.gpu/builders/mac_gpu/builds/15217)

[commit-bot: I haz the power, 2014-06-11 04:32:19]

Try jobs failed on following builders:
  mac_gpu on tryserver.chromium.gpu
(http://build.chromium.org/p/tryserver.chromium.gpu/builders/mac_gpu/builds/15283)

[oshima, 2014-06-11 14:50:45]

The CQ bit was checked by oshima@chromium.org

[commit-bot: I haz the power, 2014-06-11 14:51:44]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/oshima@chromium.org/326143002/40001

[commit-bot: I haz the power, 2014-06-11 16:13:05]

Change committed as 276421