Plumb pinch virtual viewport flag to CC.

webkit/glue/webpreferences.h

 // Copyright (c) 2012 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.
 //
 // A struct for managing webkit's settings.
 //
 // Adding new values to this class probably involves updating
 // WebKit::WebSettings, content/common/view_messages.h, browser/tab_contents/
 // render_view_host_delegate_helper.cc, and browser/profiles/profile.cc.
 
@@ skipping 139 matching lines @@
   bool deferred_image_decoding_enabled;
   bool should_respect_image_orientation;
   int number_of_cpu_cores;
   webkit_glue::EditingBehavior editing_behavior;
   bool supports_multiple_windows;
   bool viewport_enabled;
   bool initialize_at_minimum_page_scale;
   bool smart_insert_delete_enabled;
   bool spatial_navigation_enabled;
   bool experimental_websocket_enabled;
+  bool pinch_virtual_viewport_enabled;

[jamesr, 2013/05/21 17:38:35]

what does this setting have to do with Blink?

[wjmaclean, 2013/05/21 18:01:05]

The virtual viewport will require changes to the way the GraphicsLayer tree is
built, and thus this flag needs to be visible in Blink. (See the design doc Enne
put together ... "A Layer-based Solution for Fixed Position Elements and
Scrollbars Under Pinch Zoom")

[jamesr, 2013/05/22 19:35:29]

But it doesn't do anything in this patch - the bool goes nowhere.  Add it when
you add the WebSetting.  You'll have to patch this file then anyway

 
   // This flags corresponds to a Page's Settings' setCookieEnabled state. It
   // only controls whether or not the "document.cookie" field is properly
   // connected to the backing store, for instance if you wanted to be able to
   // define custom getters and setters from within a unique security content
   // without raising a DOM security exception.
   bool cookie_enabled;
 
 #if defined(OS_ANDROID)
   bool text_autosizing_enabled;
   float font_scale_factor;
   bool force_enable_zoom;
   bool double_tap_to_zoom_enabled;
   bool user_gesture_required_for_media_playback;
   GURL default_video_poster_url;
   bool support_deprecated_target_density_dpi;
   bool use_wide_viewport;
 #endif
 
   // We try to keep the default values the same as the default values in
   // chrome, except for the cases where it would require lots of extra work for
   // the embedder to use the same default value.
   WebPreferences();
   ~WebPreferences();
 };
 
 #endif  // WEBKIT_GLUE_WEBPREFERENCES_H__