Scale to legibleScale if double tap would barely zoom in from zoomed out state.

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 508 matching lines @@
     static bool mapKeyCodeForScroll(int keyCode,
                                    WebCore::ScrollDirection* scrollDirection,
                                    WebCore::ScrollGranularity* scrollGranularity);
 
     // Called by a full frame plugin inside this view to inform it that its
     // zoom level has been updated.  The plugin should only call this function
     // if the zoom change was triggered by the browser, it's only needed in case
     // a plugin can update its own zoom, say because of its own UI.
     void fullFramePluginZoomLevelChanged(double zoomLevel);
 
-    void computeScaleAndScrollForBlockRect(const WebRect& blockRect, float padding, float& scale, WebPoint& scroll, bool& doubleTapShouldZoomOut);
+    void computeScaleAndScrollForBlockRect(const WebRect& blockRect, float padding, float defaultScaleWhenAlreadyLegible, float& scale, WebPoint& scroll);
     WebCore::Node* bestTapNode(const WebCore::PlatformGestureEvent& tapEvent);
     void enableTapHighlight(const WebCore::PlatformGestureEvent& tapEvent);
     void computeScaleAndScrollForFocusedNode(WebCore::Node* focusedNode, float& scale, WebCore::IntPoint& scroll, bool& needAnimation);
 
     void animateDoubleTapZoom(const WebCore::IntPoint&);
 
     void enableFakePageScaleAnimationForTesting(bool);
     bool fakeDoubleTapAnimationPendingForTesting() const { return m_doubleTapZoomPending; }
     WebCore::IntPoint fakePageScaleAnimationTargetPositionForTesting() const { return m_fakePageScaleAnimationTargetPosition; }
     float fakePageScaleAnimationPageScaleForTesting() const { return m_fakePageScaleAnimationPageScaleFactor; }
@@ skipping 26 matching lines @@
 
     // Returns the bounding box of the block type node touched by the WebRect.
     WebRect computeBlockBounds(const WebRect&, bool ignoreClipping);
 
     WebCore::IntPoint clampOffsetAtScale(const WebCore::IntPoint& offset, float scale);
 
     // Exposed for tests.
     WebVector<WebCompositionUnderline> compositionUnderlines() const;
 
 private:
+    float legibleScale() const;
     void refreshPageScaleFactorAfterLayout();
     void setUserAgentPageScaleConstraints(WebCore::PageScaleConstraints newConstraints);
     float clampPageScaleFactorToLimits(float) const;
     WebCore::IntSize contentsSize() const;
 
     void resetSavedScrollAndScaleState();
 
     void updateMainFrameScrollPosition(const WebCore::IntPoint& scrollPosition, bool programmaticScroll);
 
     friend class WebView;  // So WebView::Create can call our constructor
@@ skipping 255 matching lines @@
 inline WebViewImpl* toWebViewImpl(WebView* webView)
 {
     // We have no ways to check if the specified WebView is an instance of
     // WebViewImpl because WebViewImpl is the only implementation of WebView.
     return static_cast<WebViewImpl*>(webView);
 }
 
 } // namespace WebKit
 
 #endif