Show Zoom Levels as content settings

content/public/browser/host_zoom_map.h

Index: content/public/browser/host_zoom_map.h
diff --git a/content/public/browser/host_zoom_map.h b/content/public/browser/host_zoom_map.h
index 72c9a1fb62f6531996b4ec72e1061a3261cc1453..930769721106ec55a76d22f33a5682f68a1cdb3c 100644
--- a/content/public/browser/host_zoom_map.h
+++ b/content/public/browser/host_zoom_map.h
@@ -49,6 +49,8 @@ class HostZoomMap {
     double zoom_level;
   };
 
+  typedef std::vector<ZoomLevelChange> ZoomLevelVector;
+
   CONTENT_EXPORT static HostZoomMap* GetForBrowserContext(
       BrowserContext* browser_context);
 
@@ -66,6 +68,9 @@ class HostZoomMap {
       const std::string& scheme,
       const std::string& host) const = 0;
 
+  // Returns all non-temporary zoom levels. Can only be called on any thread.
+  virtual ZoomLevelVector GetAllZoomLevels() const = 0;
+
   // Here |host| is the host portion of URL, or (in the absence of a host)
   // the complete spec of the URL.
   // Sets the zoom level for the |host| to |level|.  If the level matches the