GitLab

Only load theme images for the scale factors that use them

This CL implements delayed decoding of PNG data for some theme images and delayed
scaling for other scale factors until needed. Created new child of ImageSkiaSource
in BrowserThemePack for this purpose.

BUG=243831
R=pkotwicz@chromium.org
TEST=manual
out/Debug/unit_tests --gtest_filter='BrowserThemePackTest.HiDpiThemeTest'

Review URL: https://chromiumcodereview.appspot.com/16977007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@207727 0039d316-1c4b-4281-b951-d872f2087c98