Add the UI thread to the list of ChromeThreads.

chrome/browser/chrome_thread.h

 // Copyright (c) 2006-2008 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_CHROME_THREAD_H__
 #define CHROME_BROWSER_CHROME_THREAD_H__
 
 #include "base/lock.h"
 #include "base/thread.h"
 
@@ skipping 11 matching lines @@
 // thread via the g_browser_process object, e.g. g_browser_process->io_thread();
 //
 // Code that runs on a thread other than the UI thread must take extra care in
 // handling pointers to threads because many of the well-known threads are owned
 // by the UI thread and can be deallocated without notice.
 //
 class ChromeThread : public base::Thread {
  public:
   // An enumeration of the well-known threads.
   enum ID {
+    // The main thread in the browser.
+    UI,
+
     // This is the thread that processes IPC and network messages.
     IO,
 
     // This is the thread that interacts with the file system.
     FILE,
 
     // This is the thread that interacts with the database.
     DB,
 
     // This is the "main" thread for WebKit within the browser process when
@@ skipping 12 matching lines @@
 
     // This identifier does not represent a thread.  Instead it counts the
     // number of well-known threads.  Insert new well-known threads before this
     // identifier.
     ID_COUNT
   };
 
   // Construct a ChromeThread with the supplied identifier.  It is an error
   // to construct a ChromeThread that already exists.
   explicit ChromeThread(ID identifier);
+
+  // Special constructor for the main (UI) thread. We use a dummy thread here
+  // since the main thread already exists.
+  ChromeThread();
+
   virtual ~ChromeThread();
 
   // Callable on any thread, this helper function returns a pointer to the
   // thread's MessageLoop.
   //
   // WARNING:
   //   Nothing in this class prevents the MessageLoop object returned from this
   //   function from being destroyed on another thread.  Use with care.
   //
   static MessageLoop* GetMessageLoop(ID identifier);
 
   // Callable on any thread.  Returns whether you're currently on a particular
   // thread.
   //
   // WARNING:
   //   When running under unit-tests, this will return true if you're on the
   //   main thread and the thread ID you pass in isn't running.  This is
   //   normally the correct behavior because you want to ignore these asserts
   //   unless you've specifically spun up the threads, but be mindful of it.
   static bool CurrentlyOn(ID identifier);
 
  private:
+  // Common initialization code for the constructors.
+  void Initialize();
+
   // The identifier of this thread.  Only one thread can exist with a given
   // identifier at a given time.
   ID identifier_;
 
   // This lock protects |chrome_threads_|.  Do not read or modify that array
   // without holding this lock.  Do not block while holding this lock.
   static Lock lock_;
 
   // An array of the ChromeThread objects.  This array is protected by |lock_|.
   // The threads are not owned by this array.  Typically, the threads are owned
   // on the UI thread by the g_browser_process object.  ChromeThreads remove
   // themselves from this array upon destruction.
   static ChromeThread* chrome_threads_[ID_COUNT];
 };
 
 #endif  // #ifndef CHROME_BROWSER_CHROME_THREAD_H__