Limit size of scaled layer rects in ScrollbarLayer to content_bounds().

cc/test/fake_web_scrollbar.cc

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/test/fake_web_scrollbar.h"
 
 namespace cc {
 
 bool FakeWebScrollbar::isOverlay() const {
   return is_overlay_;
 }
 
 int FakeWebScrollbar::value() const {
   return 0;
 }
 
 WebKit::WebPoint FakeWebScrollbar::location() const {
-  return WebKit::WebPoint();
+  return location_;
 }
 
 WebKit::WebSize FakeWebScrollbar::size() const {
   return WebKit::WebSize();
 }
 
 bool FakeWebScrollbar::enabled() const {
   return true;
 }
 
@@ skipping 32 matching lines @@
 }
 
 bool FakeWebScrollbar::isCustomScrollbar() const {
   return false;
 }
 
 WebKit::WebScrollbar::Orientation FakeWebScrollbar::orientation() const {
   return WebScrollbar::Horizontal;
 }
 
-FakeWebScrollbar::FakeWebScrollbar() : is_overlay_(false) {}
+void FakeWebScrollbar::SetLocation(const WebKit::WebPoint& location) {
+  location_ = location;
+}
+
+FakeWebScrollbar::FakeWebScrollbar()
+    : is_overlay_(false), location_(WebKit::WebPoint()) {}
 
 }  // namespace cc