Adds scroll position/scale emulation to DevTools.

third_party/WebKit/Source/core/frame/VisualViewport.cpp

 /*
  * Copyright (C) 2013 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 53 matching lines @@
 using blink::GraphicsLayer;
 
 namespace blink {
 
 VisualViewport::VisualViewport(FrameHost& owner)
     : m_frameHost(&owner)
     , m_scale(1)
     , m_topControlsAdjustment(0)
     , m_maxPageScale(-1)
     , m_trackPinchZoomStatsForPage(false)
+    , m_scaleAndScrollOverrideEnabled(false)
+    , m_scaleAndScrollOverrideScale(0)
 {
     reset();
 }
 
 VisualViewport::~VisualViewport()
 {
     sendUMAMetrics();
 }
 
 DEFINE_TRACE(VisualViewport)
@@ skipping 119 matching lines @@
 void VisualViewport::move(const FloatSize& delta)
 {
     setLocation(m_offset + delta);
 }
 
 void VisualViewport::setScale(float scale)
 {
     setScaleAndLocation(scale, m_offset);
 }
 
+void VisualViewport::setScaleAndScrollOverride(float scale, const FloatPoint& location)
+{
+    m_scaleAndScrollOverrideEnabled = true;
+    m_scaleAndScrollOverrideScale = scale;
+    m_scaleAndScrollOverrideLocation = location;
+
+    setScaleAndLocation(this->scale(), this->location());
+}
+
+void VisualViewport::clearScaleAndScrollOverride()
+{
+    m_scaleAndScrollOverrideEnabled = false;
+    reset();
+}
+
 double VisualViewport::scrollLeft()
 {
     if (!mainFrame())
         return 0;
 
     updateStyleAndLayoutIgnorePendingStylesheets();
 
     return adjustScrollForAbsoluteZoom(visibleRect().x(), mainFrame()->pageZoomFactor());
 }
 
@@ skipping 56 matching lines @@
     return m_scale;
 }
 
 void VisualViewport::setScaleAndLocation(float scale, const FloatPoint& location)
 {
     if (!mainFrame())
         return;
 
     bool valuesChanged = false;
 
-    if (scale != m_scale) {
-        m_scale = scale;
+    float newScale = applyScaleOverrideToScale(scale);
+    if (newScale != m_scale || newScale != scale) {
+        m_scale = newScale;
         valuesChanged = true;
         frameHost().chromeClient().pageScaleFactorChanged();
     }
 
-    FloatPoint clampedOffset(clampOffsetToBoundaries(location));
+    FloatPoint overriddenLocation(applyScrollOverrideToLocation(location));
+    FloatPoint clampedOffset(clampOffsetToBoundaries(overriddenLocation));
 
-    if (clampedOffset != m_offset) {
+    // When location was overridden, re-apply override to counteract potential scroll animations by compositor.
+    if (clampedOffset != m_offset || overriddenLocation != location) {
         m_offset = clampedOffset;
         scrollAnimator().setCurrentPosition(m_offset);
 
         // SVG runs with accelerated compositing disabled so no ScrollingCoordinator.
         if (ScrollingCoordinator* coordinator = frameHost().page().scrollingCoordinator())
             coordinator->scrollableAreaScrollLayerDidChange(this);
 
         if (!frameHost().settings().inertVisualViewport()) {
             if (Document* document = mainFrame()->document())
                 document->enqueueScrollEventForNode(document);
@@ skipping 376 matching lines @@
     clampedOffset = clampedOffset.shrunkTo(FloatPoint(maximumScrollPositionDouble()));
     clampedOffset = clampedOffset.expandedTo(FloatPoint(minimumScrollPositionDouble()));
     return clampedOffset;
 }
 
 void VisualViewport::clampToBoundaries()
 {
     setLocation(m_offset);
 }
 
+FloatPoint VisualViewport::applyScrollOverrideToLocation(const FloatPoint& location)
+{
+    FloatPoint newLocation = location;
+    if (m_scaleAndScrollOverrideEnabled) {
+        if (m_scaleAndScrollOverrideLocation.x() >= 0)

[Sami, 2016/06/23 17:34:03]

Ditto.

+            newLocation.setX(m_scaleAndScrollOverrideLocation.x());
+        if (m_scaleAndScrollOverrideLocation.y() >= 0)
+            newLocation.setY(m_scaleAndScrollOverrideLocation.y());
+    }
+    return newLocation;
+}
+
+float VisualViewport::applyScaleOverrideToScale(float scale)
+{
+    if (m_scaleAndScrollOverrideEnabled && m_scaleAndScrollOverrideScale > 0)
+        return m_scaleAndScrollOverrideScale;
+    return scale;
+}
+
 FloatRect VisualViewport::viewportToRootFrame(const FloatRect& rectInViewport) const
 {
     FloatRect rectInRootFrame = rectInViewport;
     rectInRootFrame.scale(1 / scale());
     rectInRootFrame.moveBy(location());
     return rectInRootFrame;
 }
 
 IntRect VisualViewport::viewportToRootFrame(const IntRect& rectInViewport) const
 {
@@ skipping 131 matching lines @@
     } else if (graphicsLayer == m_rootTransformLayer) {
         name =  "Root Transform Layer";
     } else {
         ASSERT_NOT_REACHED();
     }
 
     return name;
 }
 
 } // namespace blink