MainFrame scrollbars should work with RFV instead of FV

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

Index: third_party/WebKit/Source/web/tests/VisualViewportTest.cpp
diff --git a/third_party/WebKit/Source/web/tests/VisualViewportTest.cpp b/third_party/WebKit/Source/web/tests/VisualViewportTest.cpp
index 418e6480cd5f46389c1a47420f68a29dbdcb0223..68af0e71715fc25b22982881f3a5c2d0e9b4041e 100644
--- a/third_party/WebKit/Source/web/tests/VisualViewportTest.cpp
+++ b/third_party/WebKit/Source/web/tests/VisualViewportTest.cpp
@@ -307,6 +307,54 @@ TEST_P(VisualViewportTest, TestResizeAtFullyScrolledPreservesViewportLocation) {
       frameView.getScrollableArea()->visibleContentRect().location());
 }
 
+// Test the main frame scrollbars take visual viewport into account.
+TEST_P(VisualViewportTest, VerifyScrollbarBehavior) {
+  // TODO(ymalik): With root layer scrolling enabled, the scroller returned
+  // by FrameView is PaintLayerScrollableArea. PLSA doesn't know about the
+  // visual viewport and thus, scrollbars aren't added when we zoom in.
+  bool rootLayerScrolls = RuntimeEnabledFeatures::rootLayerScrollingEnabled();
+
+  initializeWithDesktopSettings();
+
+  registerMockedHttpURLLoad("200-by-800-viewport.html");
+  navigateTo(m_baseURL + "200-by-800-viewport.html");
+
+  webViewImpl()->resize(IntSize(300, 200));
+
+  ScrollableArea* scroller = frame()->view()->getScrollableArea();
+
+  // Initially, there is no horizontal scrollbar since the content fits.
+  EXPECT_FALSE(scroller->horizontalScrollbar());
+  EXPECT_TRUE(scroller->verticalScrollbar());
+
+  // Scroll layout viewport.
+  webViewImpl()->mainFrame()->setScrollOffset(WebSize(0, 200));
+  EXPECT_SIZE_EQ(ScrollOffset(0, 200), scroller->scrollOffset());
+
+  webViewImpl()->setPageScaleFactor(2.0);
+
+  // Pinch-zooming should add horizontal scrollbar.
+  if (!rootLayerScrolls)
+    EXPECT_TRUE(scroller->horizontalScrollbar());
+  else
+    EXPECT_FALSE(scroller->horizontalScrollbar());
+  EXPECT_TRUE(scroller->verticalScrollbar());
+
+  // Scroll visual viewport.
+  VisualViewport& visualViewport =
+      frame()->page()->frameHost().visualViewport();
+  visualViewport.setLocation(FloatPoint(100, 100));
+  EXPECT_FLOAT_SIZE_EQ(FloatSize(100, 100), visualViewport.scrollOffset());
+
+  // Scrollbar offset should take visual viewport into account.
+  if (!rootLayerScrolls) {
+    EXPECT_FLOAT_EQ(100, scroller->horizontalScrollbar()->currentPos());
+    EXPECT_FLOAT_EQ(300, scroller->verticalScrollbar()->currentPos());
+  } else {
+    EXPECT_FLOAT_EQ(200, scroller->verticalScrollbar()->currentPos());
+  }
+}
+
 // Test that the VisualViewport works as expected in case of a scaled
 // and scrolled viewport - scroll down.
 TEST_P(VisualViewportTest, TestResizeAfterVerticalScroll) {