Introduce HostID and de-couple Extensions from "script injection System" [browser side]

chrome/browser/extensions/api/declarative_content/content_action.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 CHROME_BROWSER_EXTENSIONS_API_DECLARATIVE_CONTENT_CONTENT_ACTION_H_
 #define CHROME_BROWSER_EXTENSIONS_API_DECLARATIVE_CONTENT_CONTENT_ACTION_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 77 matching lines @@
  protected:
   friend class base::RefCounted<ContentAction>;
   virtual ~ContentAction();
 };
 
 // Action that injects a content script.
 class RequestContentScript : public ContentAction {
  public:
   struct ScriptData;
 
+  // TODO(hanxi): add RulesRegistryID to the RequestKey.
+  struct RequestKey {
+    explicit RequestKey(const std::string& host_id) : host_id(host_id) {}
+    bool operator<(const RequestKey& key) const {
+      return host_id.compare(key.host_id) < 0;
+    }
+    std::string host_id;
+  };
+
   RequestContentScript(content::BrowserContext* browser_context,
                        const Extension* extension,
                        const ScriptData& script_data);
   RequestContentScript(DeclarativeUserScriptMaster* master,
                        const Extension* extension,
                        const ScriptData& script_data);
 
   static scoped_refptr<ContentAction> Create(
       content::BrowserContext* browser_context,
       const Extension* extension,
@@ skipping 25 matching lines @@
                ApplyInfo* apply_info) const override;
 
   void Revert(const std::string& extension_id,
               const base::Time& extension_install_time,
               ApplyInfo* apply_info) const override;
 
  private:
   void InitScript(const Extension* extension, const ScriptData& script_data);
 
   void AddScript() {
-    DCHECK(master_);
+    DCHECK(master_.get());
     master_->AddScript(script_);
   }
 
   ~RequestContentScript() override;
 
   void InstructRenderProcessToInject(content::WebContents* contents,
                                      const std::string& extension_id) const;
 
   UserScript script_;
-  DeclarativeUserScriptMaster* master_;
+  linked_ptr<DeclarativeUserScriptMaster> master_;

[Devlin, 2015/01/14 16:45:08]

I don't think it's wise to make this a linked_ptr.  Instead, let's document why
the weak pointer is safe.

[Xi Han, 2015/01/14 23:46:02]

linked_ptr was removed from here. Also I have to do a sacrifice here: use a raw
pointer. I tried the WeakPtr, but it is difficult to initialize master_ in the
constructor's initialization list, and I believe it is the only way to
initialize a WeakPtr:( Please correct me if I am wrong, I would like to make it
a weak pointer as well.

[Devlin, 2015/01/16 17:05:03]

That's my bad - when I say "weak pointer", I mean c-style raw pointer (i.e., one
that is weak and "dumb").  I need to fix that.  Raw pointer is fine, as long as
we document why it is safe. :)

[Xi Han, 2015/01/19 22:40:05]

Sounds good:)

 
   DISALLOW_COPY_AND_ASSIGN(RequestContentScript);
 };
 
 typedef DeclarativeActionSet<ContentAction> ContentActionSet;
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_API_DECLARATIVE_CONTENT_CONTENT_ACTION_H_