Makes Env::is_mouse_button_down() query the native OS when appropriate.

The problem with relying on the flags set in Env is on windows and
linux non-chromeos not all events flow through the RootWindow. This
means Env is not always upto date with the real state of the OS.

I've made this so all tests continue to use existing behavior (state
of Env matches that explicitly set), where as non-tests query the OS
on windows (linux non-chromeos is TODO).

BUG=306048
TEST=none
R=ben@chromium.org

Review URL: https://codereview.chromium.org/26467004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@228476 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 228476
Revert "Move images from drawable to drawable-mdpi."

This moves images back to drawable.

BUG=306248

This reverts commit 05dc7234ccd084de79c5fa42dd3e3f1e04dc9003.

R=tedchoc@chromium.org

Review URL: https://codereview.chromium.org/27086002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@228477 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 228477