Have content/ create and destroy its own threads.

chrome/browser/io_thread.h

 // 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.
 
 #ifndef CHROME_BROWSER_IO_THREAD_H_
 #define CHROME_BROWSER_IO_THREAD_H_
 #pragma once
 
 #include <string>
 
 #include "base/basictypes.h"
+#include "base/compiler_specific.h"
+#include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
 #include "chrome/browser/net/ssl_config_service_manager.h"
 #include "chrome/browser/prefs/pref_member.h"
-#include "content/browser/browser_process_sub_thread.h"
+#include "content/public/browser/browser_thread.h"
+#include "content/public/browser/browser_thread_delegate.h"
 #include "net/base/network_change_notifier.h"
 
+// TODO(joi): Remove these in a follow-up change and IWYU in files
+// that were getting them directly or indirectly from here.
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/message_loop.h"
+#include "base/message_loop_proxy.h"
+#include "base/synchronization/lock.h"
+#include "base/threading/thread.h"
+
+class BrowserProcessImpl;
 class ChromeNetLog;
 class ExtensionEventRouterForwarder;
 class MediaInternals;
 class PrefProxyConfigTrackerImpl;
 class PrefService;
 class SystemURLRequestContextGetter;
 
 namespace net {
 class CertVerifier;
 class CookieStore;
 class DnsRRResolver;
 class FtpTransactionFactory;
 class HostResolver;
 class HttpAuthHandlerFactory;
 class HttpServerProperties;
 class HttpTransactionFactory;
 class NetworkDelegate;
 class OriginBoundCertService;
 class ProxyConfigService;
 class ProxyService;
 class SdchManager;
 class SSLConfigService;
 class URLRequestContext;
 class URLRequestContextGetter;
 class URLSecurityManager;
 }  // namespace net
 
-class IOThread : public content::BrowserProcessSubThread {
+// Contains state associated with, initialized and cleaned up on, and
+// primarily used on, the IO thread.  Also acts as a convenience
+// accessor to the Thread object for the IO thread.
+class IOThread : public content::BrowserThreadDelegate {
  public:
   struct Globals {
     Globals();
     ~Globals();
 
     struct MediaGlobals {
       MediaGlobals();
       ~MediaGlobals();
       // MediaInternals singleton used to aggregate media information.
       scoped_ptr<MediaInternals> media_internals;
@@ skipping 45 matching lines @@
   ChromeNetLog* net_log();
 
   // Returns a getter for the URLRequestContext.  Only called on the UI thread.
   net::URLRequestContextGetter* system_url_request_context_getter();
 
   // Clears the host cache.  Intended to be used to prevent exposing recently
   // visited sites on about:net-internals/#dns and about:dns pages.  Must be
   // called on the IO thread.
   void ClearHostCache();
 
- protected:
+  // Convenience method similar to base::Thread, giving access to the
+  // actual IO thread.
+  // TODO(joi): Remove this in follow-up changes.
+  MessageLoop* message_loop() const;
+
+ private:
+  // BrowserThreadDelegate implementation, runs on the IO thread.
+  // This handles initialization and destruction of state that must
+  // live on the IO thread.
   virtual void Init() OVERRIDE;
   virtual void CleanUp() OVERRIDE;
 
- private:
   // Provide SystemURLRequestContextGetter with access to
   // InitSystemRequestContext().
   friend class SystemURLRequestContextGetter;
 
+  // Global state must be initialized on the IO thread, then this
+  // method must be invoked on the UI thread.
+  void InitSystemRequestContext();
+
+  // Lazy initialization of system request context for
+  // SystemURLRequestContextGetter. To be called on IO thread only
+  // after global state has been initialized on the IO thread, and
+  // SystemRequestContext state has been initialized on the UI thread.
+  void InitSystemRequestContextOnIOThread();
+
   static void RegisterPrefs(PrefService* local_state);
 
   net::HttpAuthHandlerFactory* CreateDefaultAuthHandlerFactory(
       net::HostResolver* resolver);
 
-  void InitSystemRequestContext();
-
-  // Lazy initialization of system request context for
-  // SystemURLRequestContextGetter. To be called on IO thread.
-  void InitSystemRequestContextOnIOThread();
-
   // Returns an SSLConfigService instance.
   net::SSLConfigService* GetSSLConfigService();
 
   // The NetLog is owned by the browser process, to allow logging from other
   // threads during shutdown, but is used most frequently on the IOThread.
   ChromeNetLog* net_log_;
 
   // The ExtensionEventRouterForwarder allows for sending events to extensions
   // from the IOThread.
   ExtensionEventRouterForwarder* extension_event_router_forwarder_;
@@ skipping 36 matching lines @@
       system_url_request_context_getter_;
 
   net::SdchManager* sdch_manager_;
 
   base::WeakPtrFactory<IOThread> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(IOThread);
 };
 
 #endif  // CHROME_BROWSER_IO_THREAD_H_