Mozart: The great RectF-ication.

Clean up the Mozart interfaces to consistently use floating point
representations when manipulating abstract geometry (transforms,
clips, hit test points) and integer representations when working
with actual pixels (viewports).

BUG=
R=abarth@google.com

Review URL: https://codereview.chromium.org/1782733002 .
diff --git a/mojo/ui/associates/mock_hit_tester.cc b/mojo/ui/associates/mock_hit_tester.cc
index a16dc4b..7d8b20b 100644
--- a/mojo/ui/associates/mock_hit_tester.cc
+++ b/mojo/ui/associates/mock_hit_tester.cc
@@ -14,7 +14,7 @@
 MockHitTester::~MockHitTester() {}
 
 void MockHitTester::SetNextResult(
-    mojo::PointPtr point,
+    mojo::PointFPtr point,
     mojo::gfx::composition::HitTestResultPtr result) {
   DCHECK(point);
   DCHECK(result);
@@ -23,7 +23,7 @@
   result_ = result.Pass();
 }
 
-void MockHitTester::HitTest(mojo::PointPtr point,
+void MockHitTester::HitTest(mojo::PointFPtr point,
                             const HitTestCallback& callback) {
   DCHECK(point);