Migrate HostZoomMap to live in StoragePartition.

content/public/browser/host_zoom_map.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.
 
 #ifndef CONTENT_PUBLIC_BROWSER_HOST_ZOOM_MAP_H_
 #define CONTENT_PUBLIC_BROWSER_HOST_ZOOM_MAP_H_
 
 #include <map>
 #include <string>
 #include <vector>
 
 #include "base/basictypes.h"
 #include "base/callback.h"
 #include "base/callback_list.h"
 #include "content/common/content_export.h"
 #include "url/gurl.h"
 
 namespace content {
 
 class NavigationEntry;
 class BrowserContext;
 class ResourceContext;
+class SiteInstance;
 class WebContents;
 
 // Maps hostnames to custom zoom levels.  Written on the UI thread and read on
 // any thread.  One instance per browser context. Must be created on the UI
 // thread, and it'll delete itself on the UI thread as well.
 // Zoom can be defined at three levels: default zoom, zoom for host, and zoom
 // for host with specific scheme. Setting any of the levels leaves settings
 // for other settings intact. Getting the zoom level starts at the most
 // specific setting and progresses to the less specific: first the zoom for the
 // host and scheme pair is checked, secondly the zoom for the host only and
@@ skipping 21 matching lines @@
 
   typedef std::vector<ZoomLevelChange> ZoomLevelVector;
 
   // Extracts the URL from NavigationEntry, substituting the error page
   // URL in the event that the error page is showing.
   CONTENT_EXPORT static GURL GetURLFromEntry(const NavigationEntry* entry);
 
   CONTENT_EXPORT static HostZoomMap* GetDefaultForBrowserContext(
       BrowserContext* browser_context);
 
+  // Returns the HostZoomMap associated with this SiteInstance. The SiteInstance
+  // may serve multiple WebContents, and the HostZoomMap is the same for all of
+  // these WebContents.
+  CONTENT_EXPORT static HostZoomMap* Get(SiteInstance* instance);
+
+  // Returns the HostZoomMap associated with this WebContents. If multiple

[Charlie Reis, 2014/11/04 23:43:17]

These descriptions don't work out for out-of-process iframes.  A WebContents can
have frames from multiple different SiteInstances.

Do we expect the top-level frame's SiteInstance to dictate the zoom level for
the entire page, including all frames?  (That's how things work today, right?) 
In that case, we should clarify these comments to refer to the SiteInstance of
the WebContents's main frame.

(No need to make that work for OOPIF in this CL.)

[wjmaclean, 2014/11/05 21:55:42]

Done.

+  // WebContents share the same SiteInstance, then they share a single
+  // HostZoomMap.
+  CONTENT_EXPORT static HostZoomMap* GetForWebContents(
+      const WebContents* contents);
+
   // Returns the current zoom level for the specified WebContents. May be
   // temporary or host-specific.
   CONTENT_EXPORT static double GetZoomLevel(const WebContents* web_contents);
 
   // Sets the current zoom level for the specified WebContents. The level may
   // be temporary or host-specific depending on the particular WebContents.
   CONTENT_EXPORT static void SetZoomLevel(const WebContents* web_contents,
                                           double level);
 
   // Send an IPC to refresh any displayed error page's zoom levels. Needs to
@@ skipping 76 matching lines @@
   virtual scoped_ptr<Subscription> AddZoomLevelChangedCallback(
       const ZoomLevelChangedCallback& callback) = 0;
 
  protected:
   virtual ~HostZoomMap() {}
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_HOST_ZOOM_MAP_H_