Refactor guest view availability to be API not permission based.

chrome/browser/guest_view/guest_view_base.h

Index: chrome/browser/guest_view/guest_view_base.h
diff --git a/chrome/browser/guest_view/guest_view_base.h b/chrome/browser/guest_view/guest_view_base.h
index e42b47ce4a5beaa21fb1cf5657ebbbccb4069665..123205955975209e19ba2cb0d6f5a73949a03281 100644
--- a/chrome/browser/guest_view/guest_view_base.h
+++ b/chrome/browser/guest_view/guest_view_base.h
@@ -17,6 +17,10 @@
 
 struct RendererContentSettingRules;
 
+namespace extensions {
+class Feature;
+}
+
 // A GuestViewBase is the base class browser-side API implementation for a
 // <*view> tag. GuestViewBase maintains an association between a guest
 // WebContents and an embedder WebContents. It receives events issued from
@@ -141,11 +145,14 @@ class GuestViewBase : public content::BrowserPluginGuestDelegate,
   // to destruction.
   virtual void WillDestroy() {}
 
-  // This method is to be implemented by the derived class. It determines
-  // whether the guest view type of the derived class can be used by the
-  // provided embedder extension ID.
-  virtual bool CanEmbedderUseGuestView(
-      const std::string& embedder_extension_id) = 0;
+  // This method is to be implemented by the derived class. Access to guest
+  // views are determined by the availability of the extension Feature returned
+  // by GetFeature().
+  //
+  // This Feature should be an API feature so that it can declare the contexts

[not at google - send to devlin, 2014/08/07 00:25:29]

This comment, and the boilerplate, is making me consider whether this method
should actually return a string representing the API name.

A bit odd, and less generic, but given the comment... safer.

+  // the guest view is available in, *not* a permission which contains no
+  // context information.
+  virtual extensions::Feature* GetFeature() = 0;
 
   // This method is to be implemented by the derived class. Given a set of
   // initialization parameters, a concrete subclass of GuestViewBase can
@@ -162,6 +169,7 @@ class GuestViewBase : public content::BrowserPluginGuestDelegate,
   // newly created WebContents.
   void Init(const std::string& embedder_extension_id,
             int embedder_render_process_id,
+            content::WebContents* web_contents,

[not at google - send to devlin, 2014/08/07 00:25:29]

I think I'll just replace the |embedder_render_process_id| argument with this
|web_contents|. Rename to |embedder_web_contents|. The process ID can be
determined from the WebContents.

             const base::DictionaryValue& create_params,
             const WebContentsCreatedCallback& callback);