Fix main thread top controls scrolling to mirror CC.

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

 /*
  * Copyright (C) 2015 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 713 matching lines @@
     // Device viewport is 400px and page is width=800 but there's an element
     // that's 1600px wide so the minimum scale is 0.25 to encompass that.
     ASSERT_EQ(0.25f, webView->minimumPageScaleFactor());
 
     // The viewport will match the layout width at scale=0.5 so the height used
     // for vh should be (300 / 0.5) for the layout height + (100 / 0.5) for top
     // controls = 800.
     EXPECT_EQ(800, frame()->view()->viewportSizeForViewportUnits().height());
 }
 
+// This tests that the viewport remains anchored when top controls are brought
+// in while the document is fully scrolled. This normally causes clamping of the
+// visual viewport to keep it bounded by the layout viewport so we're testing
+// that the viewport anchoring logic is working to keep the view unchanged.
+TEST_F(TopControlsTest, MAYBE(AnchorViewportDuringTopControlsAdjustment))
+{
+    int contentHeight = 1016;
+    int layoutViewportHeight = 500;
+    int visualViewportHeight = 500;
+    int topControlsHeight = 100;
+    int pageScale = 2;
+    int minScale = 1;
+
+    // Initialize with the top controls showing.
+    WebViewImpl* webView = initialize("large-div.html");
+    webViewImpl()->setDefaultPageScaleLimits(minScale, 5);
+    webView->setTopControlsHeight(topControlsHeight, true);
+    webView->updateTopControlsState(
+        WebTopControlsBoth, WebTopControlsShown, false);
+    webView->topControls().setShownRatio(1);
+    webView->resize(WebSize(800, layoutViewportHeight));
+    webView->updateAllLifecyclePhases();
+
+    FrameView* view = frame()->view();
+    ScrollableArea* rootViewport = frame()->view()->getScrollableArea();
+
+    int expectedVisualOffset =
+        ((layoutViewportHeight + topControlsHeight / minScale) * pageScale
+        - (visualViewportHeight + topControlsHeight))
+        / pageScale;
+    int expectedLayoutOffset =
+        contentHeight - (layoutViewportHeight + topControlsHeight / minScale);
+
+    // Zoom in to 2X and fully scroll both viewports.
+    webView->setPageScaleFactor(pageScale);
+    {
+        webView->handleInputEvent(generateEvent(WebInputEvent::GestureScrollBegin));
+        webView->handleInputEvent(generateEvent(WebInputEvent::GestureScrollUpdate, 0, -10000));
+
+        ASSERT_EQ(0.f, webView->topControls().contentOffset());
+
+        EXPECT_EQ(expectedVisualOffset, visualViewport().location().y());
+        EXPECT_EQ(expectedLayoutOffset, view->layoutViewportScrollableArea()->scrollPosition().y());
+        EXPECT_EQ(expectedVisualOffset + expectedLayoutOffset, rootViewport->scrollPosition().y());

[majidvp, 2016/04/01 17:09:36]

s/expectedVisualOffset + expectedLayoutOffset/expectedRootOffset/

[bokan, 2016/04/05 17:11:40]

Done.

+
+        webView->handleInputEvent(generateEvent(WebInputEvent::GestureScrollEnd));
+    }
+
+    webView->setTopControlsHeight(topControlsHeight, false);
+    webView->resize(WebSize(800, 600));

[majidvp, 2016/04/01 17:09:36]

600? did you mean layoutViewportHeight + topControlsHeight

[bokan, 2016/04/05 17:11:40]

Done.

+    webView->updateAllLifecyclePhases();
+
+    // Commit the top controls resize so that the top controls do not shrink the
+    // layout size. This should not have moved any of the viewports.
+    int previousRootOffset = expectedVisualOffset + expectedLayoutOffset;

[majidvp, 2016/04/01 17:09:36]

You can use expectedRootOffset which should be defined before :)

[bokan, 2016/04/05 17:11:40]

Done.

+    ASSERT_EQ(expectedVisualOffset, visualViewport().location().y());
+    ASSERT_EQ(expectedLayoutOffset,
+        view->layoutViewportScrollableArea()->scrollPosition().y());
+    ASSERT_EQ(previousRootOffset, rootViewport->scrollPosition().y());
+
+    // Now scroll back up just enough to show the top controls. The top controls
+    // should shrink both viewports but the layout viewport by a greater amount.
+    // This means the visual viewport's offset must be clamped to keep it within
+    // the layout viewport. Make sure we adjust the scroll position to account
+    // for this and keep the visual viewport at the same location relative to
+    // the document (i.e. the user shouldn't see a movement).
+    {
+        webView->handleInputEvent(generateEvent(WebInputEvent::GestureScrollBegin));
+        webView->handleInputEvent(generateEvent(WebInputEvent::GestureScrollUpdate, 0, 100));

[majidvp, 2016/04/01 17:09:36]

100 is the same as topControlsHeight which may be confusing.
The logic you are testing should work for any amount of 
top control movement.

[bokan, 2016/04/05 17:11:40]

Changed to 80.

+
+        visualViewport().clampToBoundaries();
+        view->setScrollPosition(view->scrollPosition(), ProgrammaticScroll);

[majidvp, 2016/04/01 17:09:36]

Why are these clamps required?

[bokan, 2016/04/05 17:11:40]

If we don't run the anchoring logic, the viewport scroll offsets will simply
remain at the invalid scroll positions so the check below would pass. This
forces the scroll offsets to valid values.

+
+        ASSERT_EQ(100.f, webView->topControls().contentOffset());
+        EXPECT_EQ(previousRootOffset, rootViewport->scrollPosition().y());
+
+        webView->handleInputEvent(generateEvent(WebInputEvent::GestureScrollEnd));
+    }
+}
+
 } // namespace blink