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

third_party/WebKit/Source/web/WebViewImpl.cpp

 /*
  * Copyright (C) 2011, 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:
  *
  *     * 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 1819 matching lines @@
 }
 
 void WebViewImpl::resizeVisualViewport(const WebSize& newSize)
 {
     page()->frameHost().visualViewport().setSize(newSize);
     page()->frameHost().visualViewport().clampToBoundaries();
 }
 
 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())
+        ICBSize.expand(0, -topControls().height());
+
+    pageScaleConstraintsSet().didChangeInitialContainingBlockSize(ICBSize);
 
     updatePageDefinedViewportConstraints(mainFrameImpl()->frame()->document()->viewportDescription());
     updateMainFrameLayoutSize();
 
     page()->frameHost().visualViewport().setSize(m_size);
 
     if (mainFrameImpl()->frameView()) {
         if (!mainFrameImpl()->frameView()->needsLayout())
             postLayoutResize(mainFrameImpl());
     }
@@ skipping 60 matching lines @@
 {
     if (m_shouldAutoResize || m_size == newSize)
         return;
 
     if (page()->mainFrame() && !page()->mainFrame()->isLocalFrame()) {
         // Viewport resize for a remote main frame does not require any
         // particular action, but the state needs to reflect the correct size
         // 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;
     }
 
     WebLocalFrameImpl* mainFrame = mainFrameImpl();
     if (!mainFrame)
         return;
 
     FrameView* view = mainFrame->frameView();
     if (!view)
@@ skipping 1358 matching lines @@
         constraints.maximumScale = pageScaleConstraintsSet().defaultConstraints().maximumScale;
     } else {
         constraints.minimumScale = -1;
         constraints.maximumScale = -1;
     }
     page()->frameHost().setUserAgentPageScaleConstraints(constraints);
 }
 
 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
 {
     return page()->frameHost().pageScaleConstraintsSet();
 }
 
 void WebViewImpl::refreshPageScaleFactorAfterLayout()
 {
     if (!mainFrame() || !page() || !page()->mainFrame() || !page()->mainFrame()->isLocalFrame() || !page()->deprecatedLocalMainFrame()->view())
@@ skipping 782 matching lines @@
     LocalFrame* frame = webframe->frame();
     if (!m_client || !frame->isLocalRoot())
         return;
 
     if (m_shouldAutoResize) {
         WebSize frameSize = frame->view()->frameRect().size();
         if (frameSize != m_size) {
             m_size = frameSize;
 
             page()->frameHost().visualViewport().setSize(m_size);
-            pageScaleConstraintsSet().didChangeViewSize(m_size);
+            pageScaleConstraintsSet().didChangeInitialContainingBlockSize(m_size);
 
             m_client->didAutoResize(m_size);
             sendResizeEventAndRepaint();
         }
     }
 
     if (pageScaleConstraintsSet().constraintsDirty())
         refreshPageScaleFactorAfterLayout();
 
     FrameView* view = webframe->frame()->view();
@@ skipping 514 matching lines @@
 {
     // TODO(oshima): Investigate if this should return the ScreenInfo's scale factor rather than
     // page's scale factor, which can be 1 in use-zoom-for-dsf mode.
     if (!page())
         return 1;
 
     return page()->deviceScaleFactor();
 }
 
 } // namespace blink