This is in preparation for enabling HiDPI on Windows by default. Most of the changes here are replacing usage of
the ui::GetImageScale function with ui::GetScaleForScaleFactor.

The patch to remove the HiDPI switch and enable it by default will follow. This patch has been incorporated from
girard's patch ( https://codereview.chromium.org/232483005/)

BUG=149881, 362245

Review URL: https://codereview.chromium.org/294863002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@272721 0039d316-1c4b-4281-b951-d872f2087c98
8 files changed