Add touchpad pinch zoom support to Blink

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 269 matching lines @@
     virtual void acceptLanguagesChanged() override;
 
     // WebViewImpl
     void enableViewport();
     void disableViewport();
 
     float defaultMinimumPageScaleFactor() const;
     float defaultMaximumPageScaleFactor() const;
     float minimumPageScaleFactor() const;
     float maximumPageScaleFactor() const;
+    float clampPageScaleFactorToLimits(float) const;
 
     HitTestResult coreHitTestResultAt(const WebPoint&);
     void suppressInvalidations(bool enable);
     void invalidateRect(const IntRect&);
 
     void setIgnoreInputEvents(bool newValue);
     void setBackgroundColorOverride(WebColor);
     void setZoomFactorOverride(float);
 
     Color baseBackgroundColor() const { return m_baseBackgroundColor; }
@@ skipping 230 matching lines @@
     void setPageScaleFactorAndLocation(float, const FloatPoint&);
 
     void scrollAndRescaleViewports(float scaleFactor, const IntPoint& mainFrameOrigin, const FloatPoint& pinchViewportOrigin);
 
     IntRect visibleRectInDocument() const;
 
     float legibleScale() const;
     void refreshPageScaleFactorAfterLayout();
     void resumeTreeViewCommits();
     void setUserAgentPageScaleConstraints(PageScaleConstraints newConstraints);
-    float clampPageScaleFactorToLimits(float) const;
     IntSize contentsSize() const;
 
     void updateMainFrameScrollPosition(const DoublePoint& scrollPosition, bool programmaticScroll);
 
     void performResize();
 
     friend class WebView;  // So WebView::Create can call our constructor
     friend class WTF::RefCounted<WebViewImpl>;
     friend void setCurrentInputEventForTest(const WebInputEvent*);
 
@@ skipping 214 matching lines @@
 };
 
 DEFINE_TYPE_CASTS(WebViewImpl, WebWidget, widget, widget->isWebView(), widget.isWebView());
 // 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