Make document.rootScroller work properly across iframes.

third_party/WebKit/Source/web/tests/RootScrollerTest.cpp

 // Copyright 2016 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 "core/frame/FrameHost.h"
 #include "core/frame/FrameView.h"
 #include "core/frame/TopControls.h"
 #include "core/html/HTMLFrameOwnerElement.h"
 #include "core/page/Page.h"
 #include "core/page/scrolling/RootScrollerController.h"
+#include "core/paint/PaintLayerScrollableArea.h"
 #include "platform/testing/URLTestHelpers.h"
 #include "platform/testing/UnitTestHelpers.h"
 #include "public/platform/Platform.h"
 #include "public/platform/WebURLLoaderMockFactory.h"
 #include "public/web/WebCache.h"
 #include "public/web/WebConsoleMessage.h"
 #include "public/web/WebScriptSource.h"
 #include "public/web/WebSettings.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "web/WebLocalFrameImpl.h"
@@ skipping 431 matching lines @@
             innerContainer,
             exceptionState);
         mainFrameView()->updateAllLifecyclePhases();
 
         ASSERT_EQ(innerContainer, iframe->contentDocument()->rootScroller());
         ASSERT_EQ(innerContainer,
             effectiveRootScroller(iframe->contentDocument()));
     }
 }
 
+// Tests that setting an iframe as the root scroller makes the iframe the
+// effective root scroller in the parent frame.
+TEST_F(RootScrollerTest, SetRootScrollerIframeBecomesEffective)
+{
+    initialize("root-scroller-iframe.html");
+    ASSERT_EQ(nullptr, mainFrame()->document()->rootScroller());
+
+    {
+        NonThrowableExceptionState nonThrow;
+
+        // Try to set the root scroller in the main frame to be the iframe
+        // element.
+        HTMLFrameOwnerElement* iframe = toHTMLFrameOwnerElement(
+            mainFrame()->document()->getElementById("iframe"));
+
+        mainFrame()->document()->setRootScroller(iframe, nonThrow);
+
+        ASSERT_EQ(iframe, mainFrame()->document()->rootScroller());
+        ASSERT_EQ(iframe,
+            mainFrame()->document()->rootScrollerController()
+                ->effectiveRootScroller());
+
+        Element* container =
+            iframe->contentDocument()->getElementById("container");
+
+        iframe->contentDocument()->setRootScroller(container, nonThrow);
+
+        ASSERT_EQ(container, iframe->contentDocument()->rootScroller());
+        ASSERT_EQ(container,
+            iframe->contentDocument()->rootScrollerController()
+                ->effectiveRootScroller());
+        ASSERT_EQ(iframe, mainFrame()->document()->rootScroller());
+        ASSERT_EQ(iframe,
+            mainFrame()->document()->rootScrollerController()
+                ->effectiveRootScroller());
+    }
+}
+
+// Tests that the global root scroller is correctly calculated when getting the
+// root scroller layer and that the viewport apply scroll is set on it.
+TEST_F(RootScrollerTest, SetRootScrollerIframeUsesCorrectLayerAndCallback)
+{
+    initialize("root-scroller-iframe.html");
+    ASSERT_EQ(nullptr, mainFrame()->document()->rootScroller());
+
+    HTMLFrameOwnerElement* iframe = toHTMLFrameOwnerElement(
+        mainFrame()->document()->getElementById("iframe"));
+    Element* container =
+        iframe->contentDocument()->getElementById("container");
+
+    RootScrollerController* mainController =
+        mainFrame()->document()->rootScrollerController();
+
+    NonThrowableExceptionState nonThrow;
+
+    // No root scroller set, the documentElement should be the effective root
+    // and the main FrameView's scroll layer should be the layer to use.
+    {
+        ASSERT_EQ(
+            mainController->rootScrollerLayer(),
+            mainFrameView()->layerForScrolling());
+        ASSERT_TRUE(mainController->isViewportScrollCallback(
+            mainFrame()->document()->documentElement()->getApplyScroll()));
+    }
+
+    // Set a root scroller in the iframe. Since the main document didn't set a
+    // root scroller, the global root scroller shouldn't change.
+    {
+
+        iframe->contentDocument()->setRootScroller(container, nonThrow);
+
+        ASSERT_EQ(
+            mainController->rootScrollerLayer(),
+            mainFrameView()->layerForScrolling());
+        ASSERT_TRUE(mainController->isViewportScrollCallback(
+            mainFrame()->document()->documentElement()->getApplyScroll()));
+    }
+
+    // Setting the iframe as the root scroller in the main frame should now
+    // link the root scrollers so the container should now be the global root
+    // scroller.
+    {
+        mainFrame()->document()->setRootScroller(iframe, nonThrow);
+
+        ScrollableArea* containerScroller =
+            static_cast<PaintInvalidationCapableScrollableArea*>(
+                toLayoutBox(container->layoutObject())->getScrollableArea());
+
+        ASSERT_EQ(
+            mainController->rootScrollerLayer(),
+            containerScroller->layerForScrolling());
+        ASSERT_FALSE(mainController->isViewportScrollCallback(
+            mainFrame()->document()->documentElement()->getApplyScroll()));
+        ASSERT_TRUE(mainController->isViewportScrollCallback(
+            container->getApplyScroll()));
+    }
+
+    // Unsetting the root scroller in the iframe should reset its effective
+    // root scroller to the iframe's documentElement and thus the iframe's
+    // documentElement becomes the global root scroller.
+    {
+        iframe->contentDocument()->setRootScroller(nullptr, nonThrow);
+        ASSERT_EQ(
+            mainController->rootScrollerLayer(),
+            iframe->contentDocument()->view()->layerForScrolling());
+        ASSERT_FALSE(mainController->isViewportScrollCallback(
+            container->getApplyScroll()));
+        ASSERT_FALSE(mainController->isViewportScrollCallback(
+            mainFrame()->document()->documentElement()->getApplyScroll()));
+        ASSERT_TRUE(mainController->isViewportScrollCallback(
+            iframe->contentDocument()->documentElement()->getApplyScroll()));
+    }
+
+    // Finally, unsetting the main frame's root scroller should reset it to the
+    // documentElement and corresponding layer.
+    {
+        mainFrame()->document()->setRootScroller(nullptr, nonThrow);
+        ASSERT_EQ(
+            mainController->rootScrollerLayer(),
+            mainFrameView()->layerForScrolling());
+        ASSERT_TRUE(mainController->isViewportScrollCallback(
+            mainFrame()->document()->documentElement()->getApplyScroll()));
+        ASSERT_FALSE(mainController->isViewportScrollCallback(
+            container->getApplyScroll()));
+        ASSERT_FALSE(mainController->isViewportScrollCallback(
+            iframe->contentDocument()->documentElement()->getApplyScroll()));
+    }
+}
+
+TEST_F(RootScrollerTest, TestSetRootScrollerCausesViewportLayerChange)
+{
+    // TODO(bokan): Need a test that changing root scrollers actually sets the
+    // outer viewport layer on the compositor, even in the absence of other
+    // compositing changes. crbug.com/505516
+}
+
+
 // Tests that trying to set an element as the root scroller of a document inside
 // an iframe fails when that element belongs to the parent document.
 // TODO(bokan): Recent changes mean this is now possible but should be fixed.
 TEST_F(RootScrollerTest, DISABLED_TestSetRootScrollerOnElementFromOutsideIframe)
 {
     initialize("root-scroller-iframe.html");
 
     ASSERT_EQ(nullptr, mainFrame()->document()->rootScroller());
     {
         // Try to set the the root scroller of the child document to be the
@@ skipping 19 matching lines @@
             body,
             exceptionState);
 
         ASSERT_EQ(body, iframe->contentDocument()->rootScroller());
     }
 }
 
 } // namespace
 
 } // namespace blink