Compute solid-color scrollbar properties on all platforms.

It's unnecessary to gate solid-color scrollbar properties on whether
the root container masks to bounds, since the vertical adjust should
resolve to zero in this case anyway.  It's necessary to set VisibleToTotalLengthRatio
for desktop overlay scrollbars to be sized correctly.

BUG=331605
TEST=None
R=aelias

Review URL: https://codereview.chromium.org/106733005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@243721 0039d316-1c4b-4281-b951-d872f2087c98
Add inbox_app to silk page set

This CL adds an app-style widget called app-drawer to the Silk page set. The
app-drawer widget comes from https://github.com/abarth/app-widgets and is based
on Android's navigation drawer:

http://developer.android.com/design/patterns/navigation-drawer.html

R=nduca@chromium.org
TBR=boliu@chromium.org
BUG=332439

Review URL: https://codereview.chromium.org/120753003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@243722 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 243722