Add tabs.onReplaced event to notify listeners of tabs being swapped due to prerendering or instant.

chrome/browser/extensions/browser_event_router.cc

 // Copyright (c) 2012 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/browser_event_router.h"
 
 #include "base/json/json_writer.h"
 #include "base/values.h"
 #include "chrome/browser/extensions/api/extension_action/extension_page_actions_api_constants.h"
 #include "chrome/browser/extensions/api/tabs/tabs_constants.h"
@@ skipping 453 matching lines @@
 void BrowserEventRouter::TabChangedAt(WebContents* contents,
                                       int index,
                                       TabChangeType change_type) {
   TabUpdated(contents, false);
 }
 
 void BrowserEventRouter::TabReplacedAt(TabStripModel* tab_strip_model,
                                        WebContents* old_contents,
                                        WebContents* new_contents,
                                        int index) {
+  // Notify listeners that the next tabs closing or being added are due to
+  // WebContents being swapped.
+  scoped_ptr<ListValue> args(new ListValue());
+  args->Append(Value::CreateIntegerValue(
+      ExtensionTabUtil::GetTabId(new_contents)));
+  args->Append(Value::CreateIntegerValue(
+      ExtensionTabUtil::GetTabId(old_contents)));
+
+  DispatchEvent(Profile::FromBrowserContext(new_contents->GetBrowserContext()),
+                events::kOnTabSwapped,
+                args.Pass(),
+                EventRouter::USER_GESTURE_UNKNOWN);
+
   TabClosingAt(tab_strip_model, old_contents, index);
   TabInsertedAt(new_contents, index, tab_strip_model->active_index() == index);

[Matt Perry, 2012/12/18 18:04:02]

Can we remove these two calls? The downside is that extensions may have been
depending on them before, but maybe they were broken anyway.

[justinlin, 2012/12/19 23:42:42]

Yea, I thought about removing at first, but wanted to avoid breaking
functionality. The docs do say that removed events are fired when a tab is
closed, so you're probably right that it was broken and would fire when the tab
wasn't actually closed but replaced instead. Removed.

 }
 
 void BrowserEventRouter::TabPinnedStateChanged(WebContents* contents,
                                                int index) {
   TabStripModel* tab_strip = NULL;
   int tab_index;
 
   if (ExtensionTabUtil::GetTabStripModel(contents, &tab_strip, &tab_index)) {
     DictionaryValue* changed_properties = new DictionaryValue();
     changed_properties->SetBoolean(tab_keys::kPinnedKey,
@@ skipping 91 matching lines @@
 
     DispatchEventToExtension(profile,
                              extension_action.extension_id(),
                              event_name,
                              args.Pass(),
                              EventRouter::USER_GESTURE_ENABLED);
   }
 }
 
 }  // namespace extensions