ExtensionBrowserEventRouter now observes TAB_CONTENTS_DESTROYED

chrome/browser/extensions/extension_browser_event_router.cc

 // Copyright (c) 2009 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.
 
 #include "chrome/browser/extensions/extension_browser_event_router.h"
 
 #include "base/json_writer.h"
 #include "base/values.h"
 #include "chrome/browser/browser.h"
 #include "chrome/browser/profile.h"
@@ skipping 132 matching lines @@
                                                 bool foreground) {
   ListValue args;
   args.Append(ExtensionTabUtil::CreateTabValue(contents));
   std::string json_args;
   JSONWriter::Write(&args, false, &json_args);
 
   DispatchEvent(contents->profile(), events::kOnTabCreated, json_args);
 
   registrar_.Add(this, NotificationType::NAV_ENTRY_COMMITTED,
                  Source<NavigationController>(&contents->controller()));
+  
+  // Observing TAB_CONTENTS_DESTROYED is necessary because it's
+  // possible for tabs to be created, detached and then destroyed without 
+  // ever having been re-attached and closed. This happens in the case of
+  // a devtools TabContents that is opened in window, docked, then closed.
+  registrar_.Add(this, NotificationType::TAB_CONTENTS_DESTROYED,
+                 Source<TabContents>(contents));
 }
 
 void ExtensionBrowserEventRouter::TabInsertedAt(TabContents* contents,
                                                 int index,
                                                 bool foreground) {
   // If tab is new, send tab-created event.
   int tab_id = ExtensionTabUtil::GetTabId(contents);
   if (tab_entries_.find(tab_id) == tab_entries_.end()) {
     tab_entries_[tab_id] = TabEntry(contents);
 
@@ skipping 50 matching lines @@
 
   std::string json_args;
   JSONWriter::Write(&args, false, &json_args);
 
   DispatchEvent(contents->profile(), events::kOnTabRemoved, json_args);
 
   int removed_count = tab_entries_.erase(tab_id);
   DCHECK(removed_count > 0);
 
   registrar_.Remove(this, NotificationType::NAV_ENTRY_COMMITTED,
-                    Source<NavigationController>(&contents->controller()));
+      Source<NavigationController>(&contents->controller()));
+  registrar_.Remove(this, NotificationType::TAB_CONTENTS_DESTROYED,
+      Source<TabContents>(contents));
 }
 
 void ExtensionBrowserEventRouter::TabSelectedAt(TabContents* old_contents,
                                                 TabContents* new_contents,
                                                 int index,
                                                 bool user_gesture) {
   ListValue args;
   args.Append(Value::CreateIntegerValue(
       ExtensionTabUtil::GetTabId(new_contents)));
 
@@ skipping 27 matching lines @@
   std::string json_args;
   JSONWriter::Write(&args, false, &json_args);
 
   DispatchEvent(contents->profile(), events::kOnTabMoved, json_args);
 }
 
 void ExtensionBrowserEventRouter::TabUpdated(TabContents* contents,
                                              bool did_navigate) {
   int tab_id = ExtensionTabUtil::GetTabId(contents);
   std::map<int, TabEntry>::iterator i = tab_entries_.find(tab_id);
-  if(tab_entries_.end() == i) {
-    // TODO(rafaelw): Unregister EBER on TAB_CONTENTS_DESTROYED in order
-    // not to receive NAV_ENTRY_COMMITTED from objects that are allocated
-    // at the same address as previously deleted TabContents.
-    //
-    // The problem here is that NAV_ENTRY_COMMITTED is issued by the navigation
-    // controller independently from tabstrip model. One should not rely upon
-    // TabStripModelObserver events when registering / unregistering
-    // tab contents events' handlers.
-    registrar_.Remove(this, NotificationType::NAV_ENTRY_COMMITTED,
-                      Source<NavigationController>(&contents->controller()));
-    return;
-  }
+  DCHECK(tab_entries_.end() != i);
   TabEntry& entry = i->second;
 
   DictionaryValue* changed_properties = NULL;
   if (did_navigate)
     changed_properties = entry.DidNavigate(contents);
   else
     changed_properties = entry.UpdateLoadState(contents);
 
   if (changed_properties) {
     // The state of the tab (as seen from the extension point of view) has
     // changed.  Send a notification to the extension.
     ListValue args;
     args.Append(Value::CreateIntegerValue(tab_id));
     args.Append(changed_properties);
 
     std::string json_args;
     JSONWriter::Write(&args, false, &json_args);
 
     DispatchEvent(contents->profile(), events::kOnTabUpdated, json_args);
   }
 }
 
 void ExtensionBrowserEventRouter::Observe(NotificationType type,
                                           const NotificationSource& source,
                                           const NotificationDetails& details) {
   if (type == NotificationType::NAV_ENTRY_COMMITTED) {
     NavigationController* source_controller =
         Source<NavigationController>(source).ptr();
     TabUpdated(source_controller->tab_contents(), true);
+  } else if (type == NotificationType::TAB_CONTENTS_DESTROYED) {
+    // Tab was destroyed after being detached (without being re-attached).
+    TabContents* contents = Source<TabContents>(source).ptr();
+    registrar_.Remove(this, NotificationType::NAV_ENTRY_COMMITTED,
+        Source<NavigationController>(&contents->controller()));
+    registrar_.Remove(this, NotificationType::TAB_CONTENTS_DESTROYED,
+        Source<TabContents>(contents));
   } else {
     NOTREACHED();
   }
 }
 
 void ExtensionBrowserEventRouter::TabChangedAt(TabContents* contents,
                                                int index,
                                                bool loading_only) {
   TabUpdated(contents, false);
 }
@@ skipping 13 matching lines @@
   data->Set(tab_keys::kTabUrlKey, Value::CreateStringValue(url));
   object_args->Set(tab_keys::kDataKey, data);
 
   args.Append(object_args);
 
   std::string json_args;
   JSONWriter::Write(&args, false, &json_args);
 
   DispatchEvent(profile, events::kOnPageActionExecuted, json_args);
 }