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

chrome/browser/extensions/extension_user_script_loader.h

 // Copyright 2014 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_SHARED_USER_SCRIPT_MASTER_H_
-#define CHROME_BROWSER_EXTENSIONS_SHARED_USER_SCRIPT_MASTER_H_
+#ifndef CHROME_BROWSER_EXTENSIONS_EXTENSION_USER_SCRIPT_LOADER_H_
+#define CHROME_BROWSER_EXTENSIONS_EXTENSION_USER_SCRIPT_LOADER_H_
 
-#include <set>
-
-#include "base/scoped_observer.h"
+#include "base/memory/shared_memory.h"
 #include "chrome/browser/extensions/user_script_loader.h"
+#include "content/public/browser/notification_observer.h"
+#include "content/public/browser/notification_registrar.h"
 #include "extensions/browser/extension_registry_observer.h"
 #include "extensions/common/extension.h"
+#include "extensions/common/extension_set.h"
 #include "extensions/common/user_script.h"
 
 namespace content {
 class BrowserContext;
 }
 
 class Profile;
 
 namespace extensions {
 
+class ContentVerifier;
 class ExtensionRegistry;
 
-// Manages statically-defined user scripts for all extensions. Owns a
-// UserScriptLoader to which file loading and shared memory management
-// operations are delegated.
-class SharedUserScriptMaster : public ExtensionRegistryObserver {
+// UserScriptLoader for extensions.
+class ExtensionUserScriptLoader : public UserScriptLoader,
+                                  public ExtensionRegistryObserver {
  public:
-  explicit SharedUserScriptMaster(Profile* profile);
-  ~SharedUserScriptMaster() override;
-
-  // Provides access to loader state method: scripts_ready().
-  bool scripts_ready() const { return loader_.scripts_ready(); }
+  ExtensionUserScriptLoader(Profile* profile,
+                            const ConsumerID& consumer_id,
+                            bool listen_for_extension_system_loaded);
+  ~ExtensionUserScriptLoader() override;
 
  private:
+  static bool LoadScriptContent(ConsumerID* consumer_id,
+                                UserScript::File* script_file,
+                                const SubstitutionMap* localization_messages,
+                                scoped_refptr<ContentVerifier> verifier);
+
+  // UserScriptLoader implementation.
+  void UpdateConsumersInfo() override;
+  bool ready() override;
+  ContentVerifier* GetContentVerifier() override;
+  LoadUserScriptsFunctionCallback GetLoadUserScriptsFunction() override;
+  void SendUpdate(content::RenderProcessHost* process,
+                  base::SharedMemoryHandle handle_for_process,
+                  const std::set<ConsumerID>& changed_consumers) override;
+
   // ExtensionRegistryObserver implementation.
-  void OnExtensionLoaded(content::BrowserContext* browser_context,
-                         const Extension* extension) override;
   void OnExtensionUnloaded(content::BrowserContext* browser_context,
                            const Extension* extension,
                            UnloadedExtensionInfo::Reason reason) override;
 
-  // Gets an extension's scripts' metadata; i.e., gets a list of UserScript
-  // objects that contains script info, but not the contents of the scripts.
-  const std::set<UserScript> GetScriptsMetadata(const Extension* extension);
+  // Initiates script load when we have been waiting for the extension system
+  // to be ready.
+  void OnExtensionSystemReady();
 
-  // Script loader that handles loading contents of scripts into shared memory
-  // and notifying renderers of scripts in shared memory.
-  UserScriptLoader loader_;
-
-  // The profile for which the scripts managed here are installed.
-  Profile* profile_;
+  // If the extensions service has finished loading its initial set of
+  // extensions.
+  bool extension_system_ready_;
 
   ScopedObserver<ExtensionRegistry, ExtensionRegistryObserver>
       extension_registry_observer_;
 
-  DISALLOW_COPY_AND_ASSIGN(SharedUserScriptMaster);
+  base::WeakPtrFactory<ExtensionUserScriptLoader> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(ExtensionUserScriptLoader);
 };
 
 }  // namespace extensions
 
-#endif  // CHROME_BROWSER_EXTENSIONS_SHARED_USER_SCRIPT_MASTER_H_
+#endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_USER_SCRIPT_LOADER_H_