Declarative content scripts: Browser-side: per-extension shared memory regions (lazily loaded)

chrome/browser/extensions/user_script_loader.h

-// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// 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_MASTER_H_
-#define CHROME_BROWSER_EXTENSIONS_USER_SCRIPT_MASTER_H_
+#ifndef CHROME_BROWSER_EXTENSIONS_USER_SCRIPT_LOADER_H_
+#define CHROME_BROWSER_EXTENSIONS_USER_SCRIPT_LOADER_H_
 
 #include <map>
-#include <string>
+#include <set>
 
 #include "base/compiler_specific.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
 #include "base/scoped_observer.h"
-#include "content/public/browser/browser_thread.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_messages.h"
+#include "extensions/common/extension.h"
 #include "extensions/common/extension_set.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<std::string, ExtensionSet::ExtensionPathAndDefaultLocale>
+typedef std::map<ExtensionId, ExtensionSet::ExtensionPathAndDefaultLocale>
     ExtensionsInfo;
 
-// Manages a segment of shared memory that contains the user scripts the user
-// has installed.  Lives on the UI thread.
-class UserScriptMaster : public content::NotificationObserver,
+// 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 {
  public:
   // Parses the includes out of |script| and returns them in |includes|.
   static bool ParseMetadataHeader(const base::StringPiece& script_text,
                                   UserScript* script);
 
   // 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);
 
-  explicit UserScriptMaster(Profile* profile);
-  virtual ~UserScriptMaster();
+  UserScriptLoader(Profile* profile,
+                   const ExtensionId& owner_extension_id,
+                   bool listen_for_extension_system_loaded);
+  virtual ~UserScriptLoader();
 
-  // Kicks off a process on the file thread to reload scripts from disk
-  // into a new chunk of shared memory and notify renderers.
-  virtual void StartLoad();
+  // Add |scripts| to the set of scripts managed by this loader.
+  void AddScripts(const std::set<UserScript>& scripts);
 
-  // Gets the segment of shared memory for the scripts.
-  base::SharedMemory* GetSharedMemory() const {
-    return shared_memory_.get();
-  }
+  // 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.
-  bool ScriptsReady() const { return shared_memory_.get() != NULL; }
+  bool scripts_ready() const { return shared_memory_.get() != NULL; }
 
  private:
   // content::NotificationObserver implementation.
   virtual void Observe(int type,
                        const content::NotificationSource& source,
                        const content::NotificationDetails& details) OVERRIDE;
 
   // ExtensionRegistryObserver implementation.
-  virtual void OnExtensionLoaded(content::BrowserContext* browser_context,
-                                 const Extension* extension) OVERRIDE;
   virtual void OnExtensionUnloaded(
       content::BrowserContext* browser_context,
       const Extension* extension,
       UnloadedExtensionInfo::Reason reason) OVERRIDE;
 
-  // Called when ExtensionSystem is ready.
-  void OnExtensionsReady();
+  // Initiates script load when we have been waiting for the extension system
+  // to be ready.
+  void OnExtensionSystemReady();
+
+  // Return whether or not it is possible that calls to AddScripts(),

[Devlin, 2014/08/14 22:07:08]

nit: Returns

[Mark Dittmer, 2014/08/14 22:28:21]

Done.

+  // 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.
+  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
   // updated.
   void SendUpdate(content::RenderProcessHost* process,
                   base::SharedMemory* shared_memory,
-                  const std::set<std::string>& changed_extensions);
+                  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();
 
   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_;
 
-  // The IDs of the extensions which have changed since the last update sent to
-  // the renderer.
-  std::set<std::string> changed_extensions_;
+  // 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_;
 
-  // The mutually-exclusive sets of extensions that were added or removed since
-  // the last script load.
-  std::set<std::string> added_extensions_;
-  std::set<std::string> removed_extensions_;
+  // 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_;
 
   // If the extensions service has finished loading its initial set of
   // extensions.
-  bool extensions_service_ready_;
+  bool extension_system_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_;
 
-  // Listen to extension load, unloaded notifications.
+  // ID of the extension 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_;
+
+  base::WeakPtrFactory<UserScriptLoader> weak_factory_;
+
   ScopedObserver<ExtensionRegistry, ExtensionRegistryObserver>
       extension_registry_observer_;
 
-  base::WeakPtrFactory<UserScriptMaster> weak_factory_;
-
-  DISALLOW_COPY_AND_ASSIGN(UserScriptMaster);
+  DISALLOW_COPY_AND_ASSIGN(UserScriptLoader);
 };
 
 }  // namespace extensions
 
-#endif  // CHROME_BROWSER_EXTENSIONS_USER_SCRIPT_MASTER_H_
+#endif  // CHROME_BROWSER_EXTENSIONS_USER_SCRIPT_LOADER_H_