Fix crashing bug with session sync enabled and opening developer tools.

chrome/browser/ui/browser_synced_window_delegate.cc

 // Copyright (c) 2011 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/ui/browser_synced_window_delegate.h"
 
 #include <set>
 
 #include "chrome/browser/sessions/session_id.h"
 #include "chrome/browser/tabs/tab_strip_model.h"
@@ skipping 11 matching lines @@
        i != BrowserList::end(); ++i) {
     synced_window_delegates.insert((*i)->synced_window_delegate());
   }
   return synced_window_delegates;
 }
 
 // static
 const browser_sync::SyncedWindowDelegate*
     browser_sync::SyncedWindowDelegate::FindSyncedWindowDelegateWithId(
         SessionID::id_type id) {
-  return BrowserList::FindBrowserWithID(id)->synced_window_delegate();
+  Browser* browser = BrowserList::FindBrowserWithID(id);
+  // In case we don't find the browser (e.g. for Developer Tools).
+  return browser ? browser->synced_window_delegate() : NULL;
 }
 
 // BrowserSyncedWindowDelegate implementations
 
 BrowserSyncedWindowDelegate::BrowserSyncedWindowDelegate(Browser* browser)
     : browser_(browser) {}
 
 BrowserSyncedWindowDelegate::~BrowserSyncedWindowDelegate() {}
 
 bool BrowserSyncedWindowDelegate::IsTabContentsWrapperPinned(
@@ skipping 28 matching lines @@
   return browser_->is_app();
 }
 
 bool BrowserSyncedWindowDelegate::IsTypeTabbed() const {
   return browser_->is_type_tabbed();
 }
 
 bool BrowserSyncedWindowDelegate::IsTypePopup() const {
   return browser_->is_type_popup();
 }