Don't change layout size due to top control show/hide

third_party/WebKit/Source/web/WebViewImpl.cpp

Index: third_party/WebKit/Source/web/WebViewImpl.cpp
diff --git a/third_party/WebKit/Source/web/WebViewImpl.cpp b/third_party/WebKit/Source/web/WebViewImpl.cpp
index 30d37eb148d2eb45eed04007a1f343dbf575a529..61b0ee1ddb9f08e8529487f9877dd22ab1422424 100644
--- a/third_party/WebKit/Source/web/WebViewImpl.cpp
+++ b/third_party/WebKit/Source/web/WebViewImpl.cpp
@@ -1837,7 +1837,14 @@ void WebViewImpl::resizeVisualViewport(const WebSize& newSize)
 
 void WebViewImpl::performResize()
 {
-    pageScaleConstraintsSet().didChangeViewSize(m_size);
+    // We'll keep the initial containing block size from changing when the top
+    // controls hide so that the ICB will always be the same size as the
+    // viewport with the top controls shown.
+    IntSize ICBSize = m_size;
+    if (!topControls().shrinkViewport())

[aelias_OOO_until_Jul13, 2016/01/16 04:17:38]

TopControls::layoutHeight() already includes this branch.

[bokan, 2016/01/19 00:05:31]

It's actually the converse. When the top controls are hidden layoutHeight() will
be 0 but in this case we want to subtract their height from the WebView size to
keep the ICB from changing size.

+        ICBSize.expand(0, -topControls().height());
+
+    pageScaleConstraintsSet().didChangeInitialContainingBlockSize(ICBSize);
 
     updatePageDefinedViewportConstraints(mainFrameImpl()->frame()->document()->viewportDescription());
     updateMainFrameLayoutSize();
@@ -1918,7 +1925,7 @@ void WebViewImpl::resize(const WebSize& newSize)
         // so that it can be used for initalization if the main frame gets
         // swapped to a LocalFrame at a later time.
         m_size = newSize;
-        pageScaleConstraintsSet().didChangeViewSize(m_size);
+        pageScaleConstraintsSet().didChangeInitialContainingBlockSize(m_size);
         page()->frameHost().visualViewport().setSize(m_size);
         return;
     }
@@ -3294,7 +3301,11 @@ void WebViewImpl::setIgnoreViewportTagScaleLimits(bool ignore)
 
 IntSize WebViewImpl::mainFrameSize()
 {
-    return pageScaleConstraintsSet().mainFrameSize();
+    // The frame size should match the viewport size at minimum scale, since the
+    // viewport must always be contained by the frame.
+    FloatSize frameSize(m_size);
+    frameSize.scale(1 / minimumPageScaleFactor());
+    return expandedIntSize(frameSize);
 }
 
 PageScaleConstraintsSet& WebViewImpl::pageScaleConstraintsSet() const
@@ -3307,10 +3318,23 @@ void WebViewImpl::refreshPageScaleFactorAfterLayout()
     if (!mainFrame() || !page() || !page()->mainFrame() || !page()->mainFrame()->isLocalFrame() || !page()->deprecatedLocalMainFrame()->view())
         return;
     FrameView* view = page()->deprecatedLocalMainFrame()->view();
+    Document* document = mainFrameImpl()->frame()->document();
 
-    updatePageDefinedViewportConstraints(mainFrameImpl()->frame()->document()->viewportDescription());
+    float oldMinimumPSF = minimumPageScaleFactor();
+
+    updatePageDefinedViewportConstraints(document->viewportDescription());
     pageScaleConstraintsSet().computeFinalConstraints();
 
+    // If the minimum page scale factor changed, the amount we add to the layout
+    // size due to top controls for viewport units will also have changed. i.e.
+    // For 100vh we need to add the top controls to the layout size but the
+    // top controls height is scaled so that at minimum scale, 100vh covers
+    // exactly the viewport height with top controls hidden.
+    if (topControls().height() && oldMinimumPSF != minimumPageScaleFactor()) {
+        if (document->isActive())
+            document->notifyResizeForViewportUnits();

[aelias_OOO_until_Jul13, 2016/01/16 04:17:38]

Likewise a test that fails if this isn't called.

[bokan, 2016/01/19 00:05:31]

This is no longer needed now that I use the layout width scale rather than
minimum scale.

+    }
+
     int verticalScrollbarWidth = 0;
     if (view->verticalScrollbar() && !view->verticalScrollbar()->isOverlayScrollbar())
         verticalScrollbarWidth = view->verticalScrollbar()->width();
@@ -4097,7 +4121,7 @@ void WebViewImpl::layoutUpdated(WebLocalFrameImpl* webframe)
             m_size = frameSize;
 
             page()->frameHost().visualViewport().setSize(m_size);
-            pageScaleConstraintsSet().didChangeViewSize(m_size);
+            pageScaleConstraintsSet().didChangeInitialContainingBlockSize(m_size);
 
             m_client->didAutoResize(m_size);
             sendResizeEventAndRepaint();