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

chrome/browser/extensions/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_USER_SCRIPT_LOADER_H_
 #define CHROME_BROWSER_EXTENSIONS_USER_SCRIPT_LOADER_H_
 
 #include <map>
 #include <set>
 
 #include "base/compiler_specific.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/memory/shared_memory.h"
 #include "base/memory/weak_ptr.h"
 #include "base/scoped_observer.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/host_id.h"
 #include "extensions/common/user_script.h"
 
 namespace base {
 class SharedMemory;
 }
 
 namespace content {
 class BrowserContext;
 class RenderProcessHost;
 }
 
 class Profile;
 
 namespace extensions {
 
 class ContentVerifier;
-class ExtensionRegistry;
-
-typedef std::map<ExtensionId, ExtensionSet::ExtensionPathAndDefaultLocale>
-    ExtensionsInfo;
 
 // Manages one "logical unit" of user scripts in shared memory by constructing a
 // new shared memory region when the set of scripts changes. Also notifies
 // renderers of new shared memory region when new renderers appear, or when
 // script reloading completes. Script loading lives on the UI thread. Instances
 // of this class are embedded within classes with names ending in
 // UserScriptMaster. These "master" classes implement the strategy for which
 // scripts to load/unload on this logical unit of scripts.
-class UserScriptLoader : public content::NotificationObserver,
-                         public ExtensionRegistryObserver {
+class UserScriptLoader : public content::NotificationObserver {
  public:
+  using PathAndDefaultLocale = std::pair<base::FilePath, std::string>;
+  using HostsInfo = std::map<HostID, PathAndDefaultLocale>;
+
+  using SubstitutionMap = std::map<std::string, std::string>;
+  using LoadUserScriptsContentFunction =
+      base::Callback<bool(const HostID&,
+                          UserScript::File*,
+                          const SubstitutionMap*,
+                          const scoped_refptr<ContentVerifier>&)>;
+
   // Parses the includes out of |script| and returns them in |includes|.
   static bool ParseMetadataHeader(const base::StringPiece& script_text,
                                   UserScript* script);
 
+  UserScriptLoader(Profile* profile,
+                   const HostID& host_id,
+                   const scoped_refptr<ContentVerifier>& content_verifier);
+  ~UserScriptLoader() override;
+
   // A wrapper around the method to load user scripts, which is normally run on
   // the file thread. Exposed only for tests.
-  static void LoadScriptsForTest(UserScriptList* user_scripts);
-
-  UserScriptLoader(Profile* profile,
-                   const ExtensionId& owner_extension_id,
-                   bool listen_for_extension_system_loaded);
-  ~UserScriptLoader() override;
+  void LoadScriptsForTest(UserScriptList* user_scripts);
 
   // Add |scripts| to the set of scripts managed by this loader.
   void AddScripts(const std::set<UserScript>& scripts);
 
   // Remove |scripts| from the set of scripts managed by this loader.
   void RemoveScripts(const std::set<UserScript>& scripts);
 
   // Clears the set of scripts managed by this loader.
   void ClearScripts();
 
   // Initiates procedure to start loading scripts on the file thread.
   void StartLoad();
 
-  // Return true if we have any scripts ready.
+  // Returns true if we have any scripts ready.
   bool scripts_ready() const { return shared_memory_.get() != NULL; }
 
+ protected:
+  // Updates |hosts_info_| to contain info for each element of
+  // |changed_hosts_|.
+  virtual void UpdateHostsInfo(const std::set<HostID>& changed_hosts) = 0;
+
+  // Returns a function pointer of a static funcion to load user scripts.
+  // Derived classes can specify their ways to load scripts in the static
+  // function they return.
+  // Note: It has to be safe to call multiple times.
+  virtual LoadUserScriptsContentFunction GetLoadUserScriptsFunction() = 0;
+
+  // Adds the |host_id, location| to the |hosts_info_| map.
+  // Only inserts the entry to the map when the given host_id doesn't
+  // exists.
+  void AddHostInfo(const HostID& host_id, const PathAndDefaultLocale& location);
+
+  // Removes the entries with the given host_id from the |hosts_info_| map.
+  void RemoveHostInfo(const HostID& host_id);
+
+  // Sets the flag if the initial set of hosts has finished loading; if it's
+  // set to be true, calls AttempLoad() to bootstrap.
+  void SetReady(bool ready);
+
+  Profile* profile() const { return profile_; }
+  const HostID& host_id() const { return host_id_; }
+
  private:
   // content::NotificationObserver implementation.
   void Observe(int type,
                const content::NotificationSource& source,
                const content::NotificationDetails& details) override;
 
-  // ExtensionRegistryObserver implementation.
-  void OnExtensionUnloaded(content::BrowserContext* browser_context,
-                           const Extension* extension,
-                           UnloadedExtensionInfo::Reason reason) override;
-
-  // Initiates script load when we have been waiting for the extension system
-  // to be ready.
-  void OnExtensionSystemReady();
-
   // Returns whether or not it is possible that calls to AddScripts(),
   // RemoveScripts(), and/or ClearScripts() have caused any real change in the
   // set of scripts to be loaded.
   bool ScriptsMayHaveChanged() const;
 
-  // Attempt to initiate a load.
+  // Attempts to initiate a load.
   void AttemptLoad();
 
   // Called once we have finished loading the scripts on the file thread.
   void OnScriptsLoaded(scoped_ptr<UserScriptList> user_scripts,
                        scoped_ptr<base::SharedMemory> shared_memory);
 
   // Sends the renderer process a new set of user scripts. If
-  // |changed_extensions| is not empty, this signals that only the scripts from
-  // those extensions should be updated. Otherwise, all extensions will be
+  // |changed_hosts| is not empty, this signals that only the scripts from
+  // those hosts should be updated. Otherwise, all hosts will be
   // updated.
   void SendUpdate(content::RenderProcessHost* process,
                   base::SharedMemory* shared_memory,
-                  const std::set<ExtensionId>& changed_extensions);
-
-  // Add to |changed_extensions_| those extensions referred to by |scripts|.
-  void ExpandChangedExtensions(const std::set<UserScript>& scripts);
-
-  // Update |extensions_info_| to contain info for each element of
-  // |changed_extensions_|.
-  void UpdateExtensionsInfo();
+                  const std::set<HostID>& changed_hosts);
 
   bool is_loading() const {
     // Ownership of |user_scripts_| is passed to the file thread when loading.
     return user_scripts_.get() == NULL;
   }
 
   // Manages our notification registrations.
   content::NotificationRegistrar registrar_;
 
   // Contains the scripts that were found the last time scripts were updated.
   scoped_ptr<base::SharedMemory> shared_memory_;
 
   // List of scripts from currently-installed extensions we should load.
   scoped_ptr<UserScriptList> user_scripts_;
 
-  // Maps extension info needed for localization to an extension ID.
-  ExtensionsInfo extensions_info_;
+  // Maps host info needed for localization to a host ID.
+  HostsInfo hosts_info_;
 
   // The mutually-exclusive sets of scripts that were added or removed since the
   // last script load.
   std::set<UserScript> added_scripts_;
   std::set<UserScript> removed_scripts_;
 
   // Indicates whether the the collection of scripts should be cleared before
   // additions and removals on the next script load.
   bool clear_scripts_;
 
   // The IDs of the extensions which changed in the last update sent to the
   // renderer.
-  ExtensionIdSet changed_extensions_;
+  std::set<HostID> changed_hosts_;
 
-  // If the extensions service has finished loading its initial set of
-  // extensions.
-  bool extension_system_ready_;
+  // If the initial set of hosts has finished loading.
+  bool ready_;
 
   // If list of user scripts is modified while we're loading it, we note
   // that we're currently mid-load and then start over again once the load
   // finishes.  This boolean tracks whether another load is pending.
   bool pending_load_;
 
   // Whether or not we are currently loading.
   bool is_loading_;
 
   // The profile for which the scripts managed here are installed.
   Profile* profile_;
 
-  // ID of the extension that owns these scripts, if any. This is only set to a
+  // ID of the host that owns these scripts, if any. This is only set to a
   // non-empty value for declarative user script shared memory regions.
-  ExtensionId owner_extension_id_;
+  HostID host_id_;
 
-  ScopedObserver<ExtensionRegistry, ExtensionRegistryObserver>
-      extension_registry_observer_;
+  // Manages content verification of the loaded user scripts.
+  scoped_refptr<ContentVerifier> content_verifier_;
 
   base::WeakPtrFactory<UserScriptLoader> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(UserScriptLoader);
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_USER_SCRIPT_LOADER_H_