Notify DataUseTabModel of navigations and tab closures

chrome/browser/android/data_usage/data_use_tab_model.h

 // Copyright 2015 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_ANDROID_DATA_USAGE_DATA_USE_TAB_MODEL_H_
 #define CHROME_BROWSER_ANDROID_DATA_USAGE_DATA_USE_TAB_MODEL_H_
 
-#include <stdint.h>
-
+#include <list>
 #include <string>
 
 #include "base/containers/hash_tables.h"
 #include "base/gtest_prod_util.h"
 #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 "base/time/time.h"
 #include "chrome/browser/android/data_usage/tab_data_use_entry.h"
-#include "components/data_usage/core/data_use.h"
-#include "url/gurl.h"
+#include "components/sessions/core/session_id.h"
+
+namespace base {
+class SingleThreadTaskRunner;
+}
+
+namespace data_usage {
+struct DataUse;
+}
+
+class GURL;
 
 namespace chrome {
 
 namespace android {
 
 class ExternalDataUseObserver;
 
 // Models tracking and labeling of data usage within each Tab. Within each tab,
 // the model tracks the data use of a sequence of navigations in a "tracking
 // session" beginning with an entry event and ending with an exit event.
 // Typically, these events are navigations matching a URL pattern, or various
 // types of browser-initiated navigations. A single tab may have several
 // disjoint "tracking sessions" depending on the sequence of entry and exit
 // events that took place.
 class DataUseTabModel {
  public:
   // TransitionType enumerates the types of possible browser navigation events
   // and transitions.
   enum TransitionType {
     // Navigation from the omnibox to the SRP.
     TRANSITION_OMNIBOX_SEARCH,
 
     // Navigation from external apps such as AGSA app.
     // TODO(rajendrant): Remove this if not needed.
     TRANSITION_FROM_EXTERNAL_APP,
 
-    // Navigating to another app.
-    TRANSITION_TO_EXTERNAL_APP,
-
-    // Navigation from NavSuggest below omnibox.
-    TRANSITION_FROM_NAVSUGGEST,
-
     // Navigation from the omnibox when typing a URL.
     TRANSITION_OMNIBOX_NAVIGATION,
 
     // Navigation from a bookmark.
     TRANSITION_BOOKMARK,
 
     // Navigating from history.
     TRANSITION_HISTORY_ITEM,
   };
 
   // TabDataUseObserver provides the interface for getting notifications from
-  // the DataUseTabModel.
+  // the DataUseTabModel. TabDataUseObserver is called back on UI thread.
   class TabDataUseObserver {
    public:
     virtual ~TabDataUseObserver() {}
 
     // Notification callback when tab tracking sessions are started and ended.
     // The callback will be received on the same thread AddObserver was called
     // from.
-    virtual void NotifyTrackingStarting(int32_t tab_id) = 0;
-    virtual void NotifyTrackingEnding(int32_t tab_id) = 0;
+    virtual void NotifyTrackingStarting(SessionID::id_type tab_id) = 0;
+    virtual void NotifyTrackingEnding(SessionID::id_type tab_id) = 0;
   };
 
   DataUseTabModel(const ExternalDataUseObserver* data_use_observer,
                   scoped_refptr<base::SingleThreadTaskRunner> ui_task_runner);
 
   virtual ~DataUseTabModel();
 
   base::WeakPtr<DataUseTabModel> GetWeakPtr();
 
   // Notifies the DataUseTabModel of navigation events. |tab_id| is the source
   // tab of the generated event, |transition| indicates the type of the UI
   // event/transition,  |url| is the URL in the source tab, |package| indicates
   // the android package name of external application that initiated the event.
-  void OnNavigationEvent(int32_t tab_id,
+  void OnNavigationEvent(SessionID::id_type tab_id,
                          TransitionType transition,
                          const GURL& url,
                          const std::string& package);
 
   // Notifies the DataUseTabModel that tab with |tab_id| is closed. Any active
   // tracking sessions for the tab are terminated, and the tab is marked as
   // closed.
-  void OnTabCloseEvent(int32_t tab_id);
+  void OnTabCloseEvent(SessionID::id_type tab_id);
 
   // Notifies the DataUseTabModel that tracking label |label| is removed. Any
   // active tracking sessions with the label are ended.
   virtual void OnTrackingLabelRemoved(std::string label);
 
   // Gets the label for the |data_use| object. |output_label| must not be null.
   // If a tab tracking session is found that was active at the time of request
   // start of |data_use|, returns true and |output_label| is populated with its
   // label. Otherwise returns false and |output_label| is set to empty string.
   virtual 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 observers to the observer list. Must be called on IO thread.
+  // |observer| is notified on UI thread.
+  // TODO(tbansal): Remove observers that have been destroyed.
+  void AddObserver(base::WeakPtr<TabDataUseObserver> observer);
+
+ protected:
+  // Notifies the observers that a data usage tracking session started for
+  // |tab_id|. Protected for testing.
+  void NotifyObserversOfTrackingStarting(SessionID::id_type tab_id);
+
+  // Notifies the observers that an active data usage tracking session ended for
+  // |tab_id|. Protected for testing.
+  void NotifyObserversOfTrackingEnding(SessionID::id_type tab_id);
 
  private:
   friend class DataUseTabModelTest;
   friend class MockTabDataUseEntryTest;
   friend class TestDataUseTabModel;
   FRIEND_TEST_ALL_PREFIXES(DataUseTabModelTest, SingleTabTracking);
   FRIEND_TEST_ALL_PREFIXES(DataUseTabModelTest, MultipleTabTracking);
   FRIEND_TEST_ALL_PREFIXES(DataUseTabModelTest, ObserverStartEndEvents);
-  FRIEND_TEST_ALL_PREFIXES(DataUseTabModelTest, ObserverNotNotifiedAfterRemove);
   FRIEND_TEST_ALL_PREFIXES(DataUseTabModelTest,
                            MultipleObserverMultipleStartEndEvents);
   FRIEND_TEST_ALL_PREFIXES(DataUseTabModelTest, TabCloseEvent);
   FRIEND_TEST_ALL_PREFIXES(DataUseTabModelTest, TabCloseEventEndsTracking);
   FRIEND_TEST_ALL_PREFIXES(DataUseTabModelTest, OnTrackingLabelRemoved);
   FRIEND_TEST_ALL_PREFIXES(DataUseTabModelTest,
                            CompactTabEntriesWithinMaxLimit);
   FRIEND_TEST_ALL_PREFIXES(DataUseTabModelTest,
                            UnexpiredTabEntryRemovaltimeHistogram);
   FRIEND_TEST_ALL_PREFIXES(DataUseTabModelTest,
                            ExpiredInactiveTabEntryRemovaltimeHistogram);
   FRIEND_TEST_ALL_PREFIXES(DataUseTabModelTest,
                            ExpiredActiveTabEntryRemovaltimeHistogram);
 
-  typedef base::hash_map<int32_t, TabDataUseEntry> TabEntryMap;
+  typedef base::hash_map<SessionID::id_type, TabDataUseEntry> TabEntryMap;
 
   // Virtualized for unit test support.
   virtual base::TimeTicks Now() const;
 
-  // 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);
+  void StartTrackingDataUse(SessionID::id_type tab_id,
+                            const std::string& label);
 
   // Ends the current tracking session for tab with id |tab_id|.
-  void EndTrackingDataUse(int32_t tab_id);
+  void EndTrackingDataUse(SessionID::id_type tab_id);
 
   // Compacts the tab entry map |active_tabs_| by removing expired tab entries.
   // After removing expired tab entries, if the size of |active_tabs_| exceeds
   // |kMaxTabEntries|, oldest unexpired tab entries will be removed until its
   // size is |kMaxTabEntries|.
   void CompactTabEntries();
 
   // Contains the ExternalDataUseObserver. The caller must ensure that the
   // |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_;
+  // Collection of observers that receive tracking session start and end
+  // notifications. Notifications are posted on UI thread.
+  std::list<base::WeakPtr<TabDataUseObserver>> observers_;
 
   // Maintains the tracking sessions of multiple tabs.
   TabEntryMap active_tabs_;
 
   // Maximum number of tab entries to maintain session information about.
   const size_t max_tab_entries_;
 
+  // |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);
 };
 
 }  // namespace android
 
 }  // namespace chrome
 
 #endif  // CHROME_BROWSER_ANDROID_DATA_USAGE_DATA_USE_TAB_MODEL_H_