Use the DefaultSearchManager as the exclusive authority on DSE, ignoring Web Data.

chrome/browser/search_engines/default_search_manager.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_SEARCH_ENGINES_DEFAULT_SEARCH_MANAGER_H_
 #define CHROME_BROWSER_SEARCH_ENGINES_DEFAULT_SEARCH_MANAGER_H_
 
+#include "base/callback.h"
 #include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/prefs/pref_change_registrar.h"
 
 namespace base {
 class DictionaryValue;
+}
+
+namespace base {
+class DictionaryValue;
 }
 
 namespace user_prefs {
 class PrefRegistrySyncable;
 }
 
 class PrefService;
 class PrefValueMap;
 struct TemplateURLData;
 
 // DefaultSearchManager handles the loading and writing of the user's default
 // search engine selection to and from prefs.
-
 class DefaultSearchManager {
  public:
+  static const char kDefaultSearchProviderDataPrefName[];
+
   static const char kID[];
   static const char kShortName[];
   static const char kKeyword[];
   static const char kPrepopulateID[];
   static const char kSyncGUID[];
 
   static const char kURL[];
   static const char kSuggestionsURL[];
   static const char kInstantURL[];
   static const char kImageURL[];
@@ skipping 11 matching lines @@
 
   static const char kDateCreated[];
   static const char kLastModified[];
 
   static const char kUsageCount[];
   static const char kAlternateURLs[];
   static const char kSearchTermsReplacementKey[];
   static const char kCreatedByPolicy[];
   static const char kDisabledByPolicy[];
 
-  explicit DefaultSearchManager(PrefService* pref_service);
+  enum Source {
+    FROM_FALLBACK = 0,
+    FROM_USER,
+    FROM_EXTENSION,
+    FROM_POLICY,
+  };
+
+  typedef base::Callback<void(const TemplateURLData*, Source)> ObserverCallback;
+
+  DefaultSearchManager(PrefService* pref_service,
+                       const ObserverCallback& change_observer);
+
   ~DefaultSearchManager();
 
   // Register prefs needed for tracking the default search provider.
   static void RegisterProfilePrefs(user_prefs::PrefRegistrySyncable* registry);
 
   // Save default search provider pref values into the map provided.
   static void AddPrefValueToMap(base::DictionaryValue* value,
                                 PrefValueMap* pref_value_map);
 
-  // Read default search provider data from |pref_service_|.
-  bool GetDefaultSearchEngine(TemplateURLData* url);
+  // Gets a pointer to the current Default Search Engine. If NULL, indicates
+  // that Default Search is explicitly disabled. |source|, if not NULL, will be
+  // filled in with the source of the result.
+  TemplateURLData* GetDefaultSearchEngine(Source* source) const;
+
+  // Gets the source of the current Default Search Engine value.
+  Source GetDefaultSearchEngineSource() const;
 
   // Write default search provider data to |pref_service_|.
   void SetUserSelectedDefaultSearchEngine(const TemplateURLData& data);
 
-  // Clear the user's default search provider choice from |pref_service_|.
+  // Override the default search provider with an extension.
+  void SetExtensionControlledDefaultSearchEngine(const TemplateURLData& data);
+
+  // Clear the extension-provided default search engine. Does not explicitly
+  // disable Default Search.The new current default  search engine will be
+  // defined by policy, extensions, or pre-populated data.
+  void ClearExtensionControlledDefaultSearchEngine();
+
+  // Clear the user's default search provider choice from |pref_service_|. Does
+  // not explicitly disable Default Search. The new current default search
+  // engine will be defined by policy, extensions, or pre-populated data.
   void ClearUserSelectedDefaultSearchEngine();
 
  private:
+  // Handles changes to kDefaultSearchProviderData pref. This includes sync and
+  // policy changes. Calls LoadDefaultSearchEngineFromPrefs() and
+  // NotifyObserver() if the effective DSE might have changed.
+  void OnDefaultSearchPrefChanged();
+
+  // Handles changes to kSearchProviderOverrides pref. Calls
+  // LoadPrepopulatedDefaultSearch() and NotifyObserver() if the effective DSE
+  // might have changed.
+  void OnOverridesPrefChanged();
+
+  // Updates |prefs_default_search_| with values from its corresponding
+  // pre-populated search provider record, if any.
+  void MergePrefsDataWithPrepopulated();
+
+  // Reads default search provider data from |pref_service_|, updating
+  // |prefs_default_search_| and |default_search_controlled_by_policy_|.
+  // Invokes MergePrefsDataWithPrepopulated().
+  void LoadDefaultSearchEngineFromPrefs();
+
+  // Reads pre-populated search providers, which may be built-in or overridden
+  // by kSearchProviderOverrides. Updates |fallback_default_search_|. Invoke
+  // MergePrefsDataWithPrepopulated().
+  void LoadPrepopulatedDefaultSearch();
+
+  // Invokes |change_observer_| if it is not NULL.
+  void NotifyObserver();
+
   PrefService* pref_service_;
+  const ObserverCallback change_observer_;
+  PrefChangeRegistrar pref_change_registrar_;
+
+  scoped_ptr<TemplateURLData> fallback_default_search_;
+  scoped_ptr<TemplateURLData> extension_default_search_;
+  scoped_ptr<TemplateURLData> prefs_default_search_;
+
+  bool default_search_controlled_by_policy_;
 
   DISALLOW_COPY_AND_ASSIGN(DefaultSearchManager);
 };
 
 #endif  // CHROME_BROWSER_SEARCH_ENGINES_DEFAULT_SEARCH_MANAGER_H_