Introduce per-tab preferences service.

chrome/browser/prefs/pref_service.h

Index: chrome/browser/prefs/pref_service.h
diff --git a/chrome/browser/prefs/pref_service.h b/chrome/browser/prefs/pref_service.h
index 3002e9d38db81480ae78cf854f8ab7f3849b53cb..e3eeac04317a928da71837e2f12fed44d617fb80 100644
--- a/chrome/browser/prefs/pref_service.h
+++ b/chrome/browser/prefs/pref_service.h
@@ -146,6 +146,10 @@ class PrefService : public base::NonThreadSafe {
   // incognito windows).
   PrefService* CreateIncognitoPrefService(PrefStore* incognito_extension_prefs);
 
+  // Creates a per-tab copy of the pref service that shares most pref stores
+  // and allows WebKit-related preferences to be overridden on per-tab basis.
+  PrefService* CreatePrefServiceWithPerTabPrefStore();
+
   virtual ~PrefService();
 
   // Reloads the data from file. This should only be called when the importer
@@ -297,9 +301,8 @@ class PrefService : public base::NonThreadSafe {
   SyncableService* GetSyncableService();
 
  protected:
-  // Construct a new pref service, specifying the pref sources as explicit
-  // PrefStore pointers. This constructor is what CreatePrefService() ends up
-  // calling. It's also used for unit tests.
+  // Construct a new pref service. This constructor is what
+  // CreatePrefService() ends up calling and what is used for unit tests.
   PrefService(PrefStore* managed_platform_prefs,
               PrefStore* managed_cloud_prefs,
               PrefStore* extension_prefs,
@@ -307,13 +310,18 @@ class PrefService : public base::NonThreadSafe {
               PersistentPrefStore* user_prefs,
               PrefStore* recommended_platform_prefs,
               PrefStore* recommended_cloud_prefs,
-              DefaultPrefStore* default_store,
               bool async);

[Mattias Nissler (ping if slow), 2011/11/17 18:44:39]

newline before comment.

[mnaganov (inactive), 2011/11/17 19:53:32]

Done.

-
-  // The PrefNotifier handles registering and notifying preference observers.
-  // It is created and owned by this PrefService. Subclasses may access it for
-  // unit testing.
-  scoped_ptr<PrefNotifierImpl> pref_notifier_;
+  // An overloaded version that clones and specializes value store.
+  // Used for CreateIncognito and Create...PerTabPrefStore.
+  PrefService(PrefValueStore* source_store,
+              PrefStore* managed_platform_prefs,
+              PrefStore* managed_cloud_prefs,
+              PrefStore* extension_prefs,
+              PrefStore* command_line_prefs,
+              PersistentPrefStore* user_prefs,
+              PrefStore* recommended_platform_prefs,
+              PrefStore* recommended_cloud_prefs,
+              DefaultPrefStore* default_store);
 
  private:
   class PreferencePathComparator {
@@ -338,11 +346,6 @@ class PrefService : public base::NonThreadSafe {
   // Give access to ReportUserPrefChanged() and GetMutableUserPref().
   friend class subtle::ScopedUserPrefUpdateBase;
 
-  // Construct an incognito version of the pref service. Use
-  // CreateIncognitoPrefService() instead of calling this constructor directly.
-  PrefService(const PrefService& original,
-              PrefStore* incognito_extension_prefs);
-
   // Sends notification of a changed preference. This needs to be called by
   // a ScopedUserPrefUpdate if a DictionaryValue or ListValue is changed.
   void ReportUserPrefChanged(const std::string& key);
@@ -382,9 +385,9 @@ class PrefService : public base::NonThreadSafe {
   base::Value* GetMutableUserPref(const char* path,
                                   base::Value::Type type);
 
-  // The PrefValueStore provides prioritized preference values. It is created
-  // and owned by this PrefService. Subclasses may access it for unit testing.
-  scoped_ptr<PrefValueStore> pref_value_store_;
+  // The PrefNotifier handles registering and notifying preference observers.
+  // It is created and owned by this PrefService.
+  scoped_ptr<PrefNotifierImpl> pref_notifier_;
 
   // Pref Stores and profile that we passed to the PrefValueStore.
   scoped_refptr<PersistentPrefStore> user_pref_store_;
@@ -398,6 +401,10 @@ class PrefService : public base::NonThreadSafe {
   // The model associator that maintains the links with the sync db.
   scoped_ptr<PrefModelAssociator> pref_sync_associator_;
 
+  // The PrefValueStore provides prioritized preference values. It is created
+  // and owned by this PrefService. Subclasses may access it for unit testing.
+  scoped_ptr<PrefValueStore> pref_value_store_;
+
   DISALLOW_COPY_AND_ASSIGN(PrefService);
 };