Generalize browser controls adjustment for arbitrary scrollers.

third_party/WebKit/Source/core/page/scrolling/TopDocumentRootScrollerController.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/page/scrolling/TopDocumentRootScrollerController.h"
 
 #include "core/dom/Document.h"
 #include "core/dom/Element.h"
 #include "core/frame/FrameHost.h"
 #include "core/frame/FrameView.h"
+#include "core/frame/PageScaleConstraintsSet.h"
+#include "core/frame/VisualViewport.h"
 #include "core/html/HTMLFrameOwnerElement.h"
 #include "core/layout/LayoutView.h"
 #include "core/layout/compositing/PaintLayerCompositor.h"
 #include "core/page/ChromeClient.h"
 #include "core/page/Page.h"
 #include "core/page/scrolling/OverscrollController.h"
 #include "core/page/scrolling/RootScrollerUtil.h"
 #include "core/page/scrolling/ViewportScrollCallback.h"
 #include "core/paint/PaintLayer.h"
 #include "platform/scroll/ScrollableArea.h"
@@ skipping 32 matching lines @@
   if (PaintLayer* layer = area->layer()) {
     layer->setNeedsCompositingInputsUpdate();
 
     // This is needed if the root scroller is an iframe, since the iframe
     // doesn't have a scrolling/clip layer, its PLC has a container layer that
     // needs to be resized instead.
     layer->compositor()->frameViewDidChangeSize();
   }
 }
 
+ScrollableArea* TopDocumentRootScrollerController::rootScrollerArea() const {
+  return RootScrollerUtil::scrollableAreaForRootScroller(globalRootScroller());
+}
+
+IntSize TopDocumentRootScrollerController::rootScrollerVisibleArea() const {
+  if (!topDocument() || !topDocument()->view())
+    return IntSize();
+
+  float minimumPageScale =
+      m_frameHost->pageScaleConstraintsSet().finalConstraints().minimumScale;
+  int browserControlsAdjustment =
+      ceilf(m_frameHost->visualViewport().browserControlsAdjustment() /
+            minimumPageScale);
+
+  return topDocument()->view()->visibleContentSize(ExcludeScrollbars) +
+         IntSize(0, browserControlsAdjustment);
+}
+
 Element* TopDocumentRootScrollerController::findGlobalRootScrollerElement() {
   if (!topDocument())
     return nullptr;
 
   Node* effectiveRootScroller =
       &topDocument()->rootScrollerController().effectiveRootScroller();
 
   if (effectiveRootScroller->isDocumentNode())
     return topDocument()->documentElement();
 
@@ skipping 164 matching lines @@
 
 PaintLayer* TopDocumentRootScrollerController::rootScrollerPaintLayer() const {
   return RootScrollerUtil::paintLayerForRootScroller(m_globalRootScroller);
 }
 
 Element* TopDocumentRootScrollerController::globalRootScroller() const {
   return m_globalRootScroller.get();
 }
 
 }  // namespace blink