Ensure that if FrameView::isScrollable() is false, the assoc WebLayer is, too.

Source/web/tests/ScrollingCoordinatorChromiumTest.cpp

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
  *     notice, this list of conditions and the following disclaimer in the
@@ skipping 111 matching lines @@
         settings->setAcceleratedCompositingForFixedPositionEnabled(true);
         settings->setAcceleratedCompositingForOverflowScrollEnabled(true);
         settings->setAcceleratedCompositingForScrollableFramesEnabled(true);
         settings->setCompositedScrollingForFramesEnabled(true);
         settings->setFixedPositionCreatesStackingContext(true);
     }
 
     FrameTestHelpers::WebViewHelper m_helper;
 };
 
-TEST_F(ScrollingCoordinatorChromiumTest, fastScrollingByDefault)
+TEST_F(ScrollingCoordinatorChromiumTest, fastScrollingByDefaultBodyNotScrollable)
 {
     navigateTo("about:blank");
     forceFullCompositingUpdate();
 
     // Make sure the scrolling coordinator is active.
     FrameView* frameView = frame()->view();
     Page* page = frame()->page();
     ASSERT_TRUE(page->scrollingCoordinator());
     ASSERT_TRUE(page->scrollingCoordinator()->coordinatesScrollingForFrameView(frameView));
 
+    // Fast scrolling should be enabled by default, BUT if the main frame is
+    // not scrollable, then the rootScrollLayer shouldn't be scrollable either.
+    WebLayer* rootScrollLayer = getRootScrollLayer();
+    ASSERT_FALSE(rootScrollLayer->scrollable());
+    ASSERT_FALSE(rootScrollLayer->shouldScrollOnMainThread());
+    ASSERT_FALSE(rootScrollLayer->haveWheelEventHandlers());
+}
+
+TEST_F(ScrollingCoordinatorChromiumTest, fastScrollingByDefaultBodyScrollable)
+{
+    registerMockedHttpURLLoad("body-overflow-visible.html");
+    navigateTo(m_baseURL + "body-overflow-visible.html");
+    forceFullCompositingUpdate();
+
+    // Make sure the scrolling coordinator is active.
+    FrameView* frameView = frame()->view();
+    Page* page = frame()->page();
+    ASSERT_TRUE(page->scrollingCoordinator());
+    ASSERT_TRUE(page->scrollingCoordinator()->coordinatesScrollingForFrameView(frameView));
+
     // Fast scrolling should be enabled by default.
     WebLayer* rootScrollLayer = getRootScrollLayer();
     ASSERT_TRUE(rootScrollLayer->scrollable());
     ASSERT_FALSE(rootScrollLayer->shouldScrollOnMainThread());
     ASSERT_FALSE(rootScrollLayer->haveWheelEventHandlers());
 }
 
 static WebLayer* webLayerFromElement(Element* element)
 {
     if (!element)
@@ skipping 313 matching lines @@
 TEST_F(ScrollingCoordinatorChromiumTest, setupScrollbarLayerShouldNotCrash)
 {
     registerMockedHttpURLLoad("setup_scrollbar_layer_crash.html");
     navigateTo(m_baseURL + "setup_scrollbar_layer_crash.html");
     forceFullCompositingUpdate();
     // This test document setup an iframe with scrollbars, then switch to
     // an empty document by javascript.
 }
 
 } // namespace