Adds ComboboxModelObserver to ComboboxModel

I'm going to need this so that I can make
RecentlyUsedFoldersComboModel notify observers when it changes.

BUG=294330
TEST=none
R=msw@chromium.org

Review URL: https://codereview.chromium.org/25146009

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@226304 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 226304
Fix code style and gyp files in cast to build cast_unittest

*.gypi should not be used for dependency directly. Renaming those files
to *.gyp. Also style fixes to make compilers happy.

This change is reland of r226264.

TBR=acolwell

Review URL: https://codereview.chromium.org/25544003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@226305 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 226305
Create standalone TouchEventQueue unit tests

Move TouchEventQueue-related tests from the general router tests to the more
specific TouchEventQueueTest.  Create MockWeb*EventBuilder utility classes for
testing, factoring out usage from RenderWidgetHostTest and InputRouterTest.


BUG=301838

Review URL: https://codereview.chromium.org/25102005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@226306 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 226306