mac: Only let two-finger-scrolling trigger history if web doesn't swallow gesture

chrome/browser/renderer_host/render_widget_host_view_mac.h

 // Copyright (c) 2011 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.
 
 #ifndef CHROME_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_MAC_H_
 #define CHROME_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_MAC_H_
 #pragma once
 
 #import <Cocoa/Cocoa.h>
 
@@ skipping 99 matching lines @@
   EditCommands editCommands_;
 
   // The plugin that currently has focus (-1 if no plugin has focus).
   int focusedPluginIdentifier_;
 
   // Whether or not plugin IME is currently enabled active.
   BOOL pluginImeActive_;
 
   // Whether the previous mouse event was ignored due to hitTest check.
   BOOL mouseEventWasIgnored_;
+
+  // If a scroll event came back unhandled from the renderer.
+  // Used for history swiping.
+  BOOL gotUnhandledWheelEvent_;

[Mark Mentovai, 2011/08/15 14:43:57]

Document which of these fields (I guess gotUnhandledWheelEvent_ and
totalScrollDelta_) are only valid within the duration of a gesture.

+
+  // Cummulative scroll delta since scroll gesture start.
+  // Used for history swiping.
+  NSSize totalScrollDelta_;
+
+  // If the viewport is scrolled all the way to the left or right.
+  // Used for history swiping.
+  BOOL isPinnedLeft_;
+  BOOL isPinnedRight_;
+
+  // If the main frame has a horizontal scrollbar.
+  // Used for history swiping.
+  BOOL hasHorizontalScrollbar_;
 }
 
 @property(nonatomic, readonly) NSRange selectedRange;
+@property(nonatomic) BOOL gotUnhandledWheelEvent;
+@property(nonatomic, setter=setPinnedLeft:) BOOL isPinnedLeft;
+@property(nonatomic, setter=setPinnedRight:) BOOL isPinnedRight;
+@property(nonatomic) BOOL hasHorizontalScrollbar;
 
 - (void)setCanBeKeyView:(BOOL)can;
 - (void)setTakesFocusOnlyOnMouseDown:(BOOL)b;
 - (void)setCloseOnDeactivate:(BOOL)b;
 - (void)setToolTipAtMousePoint:(NSString *)string;
 // Set frame, then notify the RenderWidgetHost that the frame has been changed,
 // but do it in a separate task, using |performSelector:withObject:afterDelay:|.
 // This stops the flickering issue in http://crbug.com/31970
 - (void)setFrameWithDeferredUpdate:(NSRect)frame;
 // Notify the RenderWidgetHost that the frame was updated so it can resize
@@ skipping 140 matching lines @@
   void DrawAcceleratedSurfaceInstance(
       CGLContextObj context,
       gfx::PluginWindowHandle plugin_handle,
       NSSize size);
   // Forces the textures associated with any accelerated plugin instances
   // to be reloaded.
   void ForceTextureReload();
 
   virtual void SetVisuallyDeemphasized(const SkColor* color, bool animate);
 
+  virtual void UnhandledWheelEvent(
+      const WebKit::WebMouseWheelEvent& event) OVERRIDE;
+  virtual void SetHasHorizontalScrollbar(
+      bool has_horizontal_scrollbar) OVERRIDE;
+  virtual void SetScrollOffsetPinning(
+      bool is_pinned_to_left, bool is_pinned_to_right) OVERRIDE;
+
   void KillSelf();
 
   void SetTextInputActive(bool active);
 
   // Sends completed plugin IME notification and text back to the renderer.
   void PluginImeCompositionCompleted(const string16& text, int plugin_id);
 
   const std::string& selected_text() const { return selected_text_; }
 
   void UpdateRootGpuViewVisibility(bool show_gpu_widget);
@@ skipping 98 matching lines @@
   // hidden until the software backing store has been updated. This variable is
   // set when the gpu widget needs to be hidden once a paint is completed.
   bool needs_gpu_visibility_update_after_repaint_;
 
   gfx::PluginWindowHandle compositing_surface_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderWidgetHostViewMac);
 };
 
 #endif  // CHROME_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_MAC_H_