Adds scroll position/scale emulation to DevTools.

third_party/WebKit/Source/web/WebViewImpl.h

 /*
  * Copyright (C) 2010 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 31 matching lines @@
 #include "public/platform/WebDisplayMode.h"
 #include "public/platform/WebFloatSize.h"
 #include "public/platform/WebGestureCurveTarget.h"
 #include "public/platform/WebInputEventResult.h"
 #include "public/platform/WebLayer.h"
 #include "public/platform/WebPoint.h"
 #include "public/platform/WebRect.h"
 #include "public/platform/WebSize.h"
 #include "public/platform/WebString.h"
 #include "public/platform/WebVector.h"
+#include "public/web/WebDeviceEmulationParams.h"
 #include "public/web/WebInputEvent.h"
 #include "public/web/WebNavigationPolicy.h"
 #include "public/web/WebPageImportanceSignals.h"
 #include "public/web/WebView.h"
 #include "web/ChromeClientImpl.h"
 #include "web/ContextMenuClientImpl.h"
 #include "web/EditorClientImpl.h"
 #include "web/MediaKeysClientImpl.h"
 #include "web/PageWidgetDelegate.h"
 #include "web/SpellCheckerClientImpl.h"
@@ skipping 136 matching lines @@
     double setZoomLevel(double) override;
     void zoomLimitsChanged(double minimumZoomLevel, double maximumZoomLevel) override;
     float textZoomFactor() override;
     float setTextZoomFactor(float) override;
     bool zoomToMultipleTargetsRect(const WebRect&) override;
     float pageScaleFactor() const override;
     void setDefaultPageScaleLimits(float minScale, float maxScale) override;
     void setInitialPageScaleOverride(float) override;
     void setMaximumLegibleScale(float) override;
     void setPageScaleFactor(float) override;
+    WebPoint mainFrameOffset() const override;
     void setVisualViewportOffset(const WebFloatPoint&) override;
     WebFloatPoint visualViewportOffset() const override;
     WebFloatSize visualViewportSize() const override;
     void resetScrollAndScaleState() override;
     void setIgnoreViewportTagScaleLimits(bool) override;
     WebSize contentsPreferredMinimumSize() override;
     void setDisplayMode(WebDisplayMode) override;
 
     void setDeviceScaleFactor(float) override;
     void setZoomFactorForDeviceScaleFactor(float) override;
@@ skipping 313 matching lines @@
     double lastFrameTimeMonotonic() const { return m_lastFrameTimeMonotonic; }
 
     ChromeClientImpl& chromeClient() const { return *m_chromeClientImpl.get(); }
 
 private:
     InspectorOverlay* inspectorOverlay();
 
     void setPageScaleFactorAndLocation(float, const FloatPoint&);
     void propagateZoomFactorToLocalFrameRoots(Frame*, float);
 
+    // Override the page scale and scroll positions of main frame and visual viewport.
+    void setScrollOverride(const WebDeviceEmulationParams&);
+
+    // Clear the page scale and scroll position overrides.
+    void clearScrollOverride();
+
     void scrollAndRescaleViewports(float scaleFactor, const IntPoint& mainFrameOrigin, const FloatPoint& visualViewportOrigin);
 
     float maximumLegiblePageScale() const;
     void refreshPageScaleFactorAfterLayout();
     IntSize contentsSize() const;
 
     void performResize();
     void resizeViewWhileAnchored(FrameView*, float topControlsHeight, bool topControlsShrinkLayout);
 
     friend class WebView;  // So WebView::Create can call our constructor
@@ skipping 120 matching lines @@
     float m_doubleTapZoomPageScaleFactor;
     // Have we sent a double-tap zoom and not yet heard back the scale?
     bool m_doubleTapZoomPending;
 
     // Used for testing purposes.
     bool m_enableFakePageScaleAnimationForTesting;
     IntPoint m_fakePageScaleAnimationTargetPosition;
     float m_fakePageScaleAnimationPageScaleFactor;
     bool m_fakePageScaleAnimationUseAnchor;
 
+    bool m_scrollOverrideEnabled;
+    WebDeviceEmulationParams m_scrollOverrideParams;

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

This is a pretty hefty object -- should we instead just store the couple of
fields we need here?

[Eric Seckler, 2016/06/23 18:12:43]

I agree, I will do that in combination with David's suggestion to extract the
data and some of the logic for applying overrides (e.g.
VisualViewport::applyScrollOverrideToLocation()) into a separate class.

I was experimenting with making the VisualViewport::setSize() call in
WebViewImpl::performResize() dependent on whether a visual viewport size
override is set (see WebViewImpl.cpp in patch) to avoid crbug.com/620772 for our
use cases. I'll remove that in the process as it is a little ugly - There's no
other reason why WebViewImpl (or the new class for scroll overrides) should know
about viewport sizes. Does that make sense?

+
     bool m_doingDragAndDrop;
 
     bool m_ignoreInputEvents;
 
     float m_compositorDeviceScaleFactorOverride;
     WebSize m_rootLayerOffset;
     float m_rootLayerScale;
 
     // Webkit expects keyPress events to be suppressed if the associated keyDown
     // event was handled. Safari implements this behavior by peeking out the
@@ skipping 76 matching lines @@
     double m_lastFrameTimeMonotonic;
 };
 
 // We have no ways to check if the specified WebView is an instance of
 // WebViewImpl because WebViewImpl is the only implementation of WebView.
 DEFINE_TYPE_CASTS(WebViewImpl, WebView, webView, true, true);
 
 } // namespace blink
 
 #endif