Notify DataUseTabModel of navigations and tab closures

chrome/browser/android/data_usage/data_use_tab_model.h

Index: chrome/browser/android/data_usage/data_use_tab_model.h
diff --git a/chrome/browser/android/data_usage/data_use_tab_model.h b/chrome/browser/android/data_usage/data_use_tab_model.h
index 43a07bdb110c5a8ac329cb20af38617e10afe9e3..311d27da99f78272296976683b284d7f68f7dbe4 100644
--- a/chrome/browser/android/data_usage/data_use_tab_model.h
+++ b/chrome/browser/android/data_usage/data_use_tab_model.h
@@ -14,7 +14,6 @@
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
-#include "base/observer_list_threadsafe.h"
 #include "base/threading/thread_checker.h"
 #include "chrome/browser/android/data_usage/tab_data_use_entry.h"
 #include "components/data_usage/core/data_use.h"

[sclittle, 2015/11/20 22:50:54]

Replace this include with a forward declaration of DataUse.

[tbansal1, 2015/11/23 17:52:22]

Done.

@@ -62,7 +61,7 @@ class DataUseTabModel {
   };
 
   // TabDataUseObserver provides the interface for getting notifications from
-  // the DataUseTabModel.
+  // the DataUseTabModel. TabDataUseObserver is called back on UI thread.
   class TabDataUseObserver {
    public:
     virtual ~TabDataUseObserver() {}
@@ -102,10 +101,20 @@ class DataUseTabModel {
   bool GetLabelForDataUse(const data_usage::DataUse& data_use,
                           std::string* output_label) const;
 
-  // Adds or removes observers from the observer list. These functions are
-  // thread-safe and can be called from any thread.
-  void AddObserver(TabDataUseObserver* observer);
-  void RemoveObserver(TabDataUseObserver* observer);
+  // Adds or removes observers from the observer list. Must be called only on
+  // IO thread. |weak_ptr_observer| is notified on UI thread.
+  void AddObserver(const TabDataUseObserver* observer,
+                   const base::WeakPtr<TabDataUseObserver>& weak_ptr_observer);
+  void RemoveObserver(const TabDataUseObserver* observer);
+
+ protected:
+  // Notifies the observers that a data usage tracking session started for
+  // |tab_id|. Protected for testing.
+  void NotifyObserversOfTrackingStarting(int32_t tab_id);
+
+  // Notifies the observers that an active data usage tracking session ended for
+  // |tab_id|. Protected for testing.
+  void NotifyObserversOfTrackingEnding(int32_t tab_id);
 
  private:
   friend class DataUseTabModelTest;
@@ -121,20 +130,14 @@ class DataUseTabModel {
   FRIEND_TEST_ALL_PREFIXES(DataUseTabModelTest,
                            CompactTabEntriesWithinMaxLimit);
 
+  typedef base::hash_map<const TabDataUseObserver*,
+                         const base::WeakPtr<TabDataUseObserver>&> ObserverMap;
   typedef base::hash_map<int32_t, TabDataUseEntry> TabEntryMap;
 
   // Returns the maximum number of tab entries to maintain session information
   // about.
   static size_t GetMaxTabEntriesForTests();
 
-  // Notifies the observers that a data usage tracking session started for
-  // |tab_id|.
-  void NotifyObserversOfTrackingStarting(int32_t tab_id);
-
-  // Notifies the observers that an active data usage tracking session ended for
-  // |tab_id|.
-  void NotifyObserversOfTrackingEnding(int32_t tab_id);
-
   // Initiates a new tracking session with the |label| for tab with id |tab_id|.
   void StartTrackingDataUse(int32_t tab_id, const std::string& label);
 
@@ -151,17 +154,19 @@ class DataUseTabModel {
   // |data_use_observer_| outlives this instance.
   const ExternalDataUseObserver* data_use_observer_;
 
-  // List of observers waiting for tracking session start and end notifications.
-  const scoped_refptr<base::ObserverListThreadSafe<TabDataUseObserver>>
-      observer_list_;
+  // Map of observers waiting for tracking session start and end notifications.
+  // Map is keyed by raw pointers, and notifications are posted to the weak
+  // pointers on UI thread.
+  ObserverMap observers_;
 
   // Maintains the tracking sessions of multiple tabs.
   TabEntryMap active_tabs_;
 
+  // |ui_task_runner_| is used to notify TabDataUseObserver on UI thread.
+  scoped_refptr<base::SingleThreadTaskRunner> ui_task_runner_;
+
   base::ThreadChecker thread_checker_;
 
-  // |weak_factory_| is used for generating weak pointers to be passed to
-  // DataUseTabUIManager on the UI thread.
   base::WeakPtrFactory<DataUseTabModel> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(DataUseTabModel);