Revert 111695 - Have content/ create and destroy its own threads.

content/browser/browser_thread_impl.cc

Index: content/browser/browser_thread_impl.cc
===================================================================
--- content/browser/browser_thread_impl.cc	(revision 111697)
+++ content/browser/browser_thread_impl.cc	(working copy)
@@ -4,19 +4,16 @@
 
 #include "content/browser/browser_thread_impl.h"
 
-#include "base/atomicops.h"
 #include "base/bind.h"
 #include "base/lazy_instance.h"
 #include "base/message_loop.h"
 #include "base/message_loop_proxy.h"
 #include "base/threading/thread_restrictions.h"
 
-namespace content {
-
 namespace {
 
 // Friendly names for the well-known threads.
-static const char* g_browser_thread_names[BrowserThread::ID_COUNT] = {
+static const char* browser_thread_names[content::BrowserThread::ID_COUNT] = {
   "",  // UI (name assembled in browser_main.cc).
   "Chrome_DBThread",  // DB
   "Chrome_WebKitThread",  // WEBKIT
@@ -29,86 +26,38 @@
 #endif
 };
 
-// This lock protects |g_browser_threads|.  Do not read or modify that
-// array without holding this lock.  Do not block while holding this
-// lock.
+}  // namespace
+
+namespace content {
+
+namespace {
+
+// This lock protects |g_browser_threads|.  Do not read or modify that array
+// without holding this lock.  Do not block while holding this lock.
 base::LazyInstance<base::Lock,
                    base::LeakyLazyInstanceTraits<base::Lock> >
     g_lock = LAZY_INSTANCE_INITIALIZER;
 
-// This array is protected by |g_lock|.  The threads are not owned by this
-// array. Typically, the threads are owned on the UI thread by
-// content::BrowserMainLoop.  BrowserThreadImpl objects remove
+
+// An array of the BrowserThread objects.  This array is protected by |g_lock|.
+// The threads are not owned by this array.  Typically, the threads are owned
+// on the UI thread by the g_browser_process object.  BrowserThreads remove
 // themselves from this array upon destruction.
-static BrowserThreadImpl* g_browser_threads[BrowserThread::ID_COUNT];
+BrowserThread* g_browser_threads[BrowserThread::ID_COUNT];
 
-// Only atomic operations are used on this array.  The delegates are
-// not owned by this array, rather by whoever calls
-// BrowserThread::SetDelegate.
-static BrowserThreadDelegate* g_browser_thread_delegates[
-    BrowserThread::ID_COUNT];
-
 }  // namespace
 
-BrowserThreadImpl::BrowserThreadImpl(ID identifier)
-    : Thread(g_browser_thread_names[identifier]),
-      identifier_(identifier) {
-  Initialize();
+BrowserThreadImpl::BrowserThreadImpl(BrowserThread::ID identifier)
+    : BrowserThread(identifier) {
 }
 
-BrowserThreadImpl::BrowserThreadImpl(ID identifier,
+BrowserThreadImpl::BrowserThreadImpl(BrowserThread::ID identifier,
                                      MessageLoop* message_loop)
-    : Thread(message_loop->thread_name().c_str()),
-      identifier_(identifier) {
-  set_message_loop(message_loop);
-  Initialize();
+    : BrowserThread(identifier, message_loop) {
 }
 
-void BrowserThreadImpl::Init() {
-  using base::subtle::AtomicWord;
-  AtomicWord* storage =
-      reinterpret_cast<AtomicWord*>(&g_browser_thread_delegates[identifier_]);
-  AtomicWord stored_pointer = base::subtle::NoBarrier_Load(storage);
-  BrowserThreadDelegate* delegate =
-      reinterpret_cast<BrowserThreadDelegate*>(stored_pointer);
-  if (delegate)
-    delegate->Init();
-}
-
-void BrowserThreadImpl::CleanUp() {
-  using base::subtle::AtomicWord;
-  AtomicWord* storage =
-      reinterpret_cast<AtomicWord*>(&g_browser_thread_delegates[identifier_]);
-  AtomicWord stored_pointer = base::subtle::NoBarrier_Load(storage);
-  BrowserThreadDelegate* delegate =
-      reinterpret_cast<BrowserThreadDelegate*>(stored_pointer);
-
-  if (delegate)
-    delegate->CleanUp();
-}
-
-void BrowserThreadImpl::Initialize() {
-  base::AutoLock lock(g_lock.Get());
-  DCHECK(identifier_ >= 0 && identifier_ < ID_COUNT);
-  DCHECK(g_browser_threads[identifier_] == NULL);
-  g_browser_threads[identifier_] = this;
-}
-
 BrowserThreadImpl::~BrowserThreadImpl() {
-  // All Thread subclasses must call Stop() in the destructor. This is
-  // doubly important here as various bits of code check they are on
-  // the right BrowserThread.
   Stop();
-
-  base::AutoLock lock(g_lock.Get());
-  g_browser_threads[identifier_] = NULL;
-#ifndef NDEBUG
-  // Double check that the threads are ordered correctly in the enumeration.
-  for (int i = identifier_ + 1; i < ID_COUNT; ++i) {
-    DCHECK(!g_browser_threads[i]) <<
-        "Threads must be listed in the reverse order that they die";
-  }
-#endif
 }
 
 // static
@@ -128,7 +77,7 @@
   BrowserThread::ID current_thread;
   bool guaranteed_to_outlive_target_thread =
       GetCurrentThreadIdentifier(&current_thread) &&
-      current_thread <= identifier;
+      current_thread >= identifier;
 
   if (!guaranteed_to_outlive_target_thread)
     g_lock.Get().Acquire();
@@ -169,7 +118,7 @@
   BrowserThread::ID current_thread;
   bool guaranteed_to_outlive_target_thread =
       GetCurrentThreadIdentifier(&current_thread) &&
-      current_thread <= identifier;
+      current_thread >= identifier;
 
   if (!guaranteed_to_outlive_target_thread)
     g_lock.Get().Acquire();
@@ -190,6 +139,18 @@
   return !!message_loop;
 }
 
+// TODO(joi): Remove
+DeprecatedBrowserThread::DeprecatedBrowserThread(BrowserThread::ID identifier)
+    : BrowserThread(identifier) {
+}
+DeprecatedBrowserThread::DeprecatedBrowserThread(BrowserThread::ID identifier,
+                                                 MessageLoop* message_loop)
+    : BrowserThread(identifier, message_loop) {
+}
+DeprecatedBrowserThread::~DeprecatedBrowserThread() {
+  Stop();
+}
+
 // An implementation of MessageLoopProxy to be used in conjunction
 // with BrowserThread.
 class BrowserThreadMessageLoopProxy : public base::MessageLoopProxy {
@@ -254,6 +215,44 @@
   DISALLOW_COPY_AND_ASSIGN(BrowserThreadMessageLoopProxy);
 };
 
+BrowserThread::BrowserThread(ID identifier)
+    : Thread(browser_thread_names[identifier]),
+      identifier_(identifier) {
+  Initialize();
+}
+
+BrowserThread::BrowserThread(ID identifier,
+                             MessageLoop* message_loop)
+    : Thread(message_loop->thread_name().c_str()),
+      identifier_(identifier) {
+  set_message_loop(message_loop);
+  Initialize();
+}
+
+void BrowserThread::Initialize() {
+  base::AutoLock lock(g_lock.Get());
+  DCHECK(identifier_ >= 0 && identifier_ < ID_COUNT);
+  DCHECK(g_browser_threads[identifier_] == NULL);
+  g_browser_threads[identifier_] = this;
+}
+
+BrowserThread::~BrowserThread() {
+  // Stop the thread here, instead of the parent's class destructor.  This is so
+  // that if there are pending tasks that run, code that checks that it's on the
+  // correct BrowserThread succeeds.
+  Stop();
+
+  base::AutoLock lock(g_lock.Get());
+  g_browser_threads[identifier_] = NULL;
+#ifndef NDEBUG
+  // Double check that the threads are ordered correctly in the enumeration.
+  for (int i = identifier_ + 1; i < ID_COUNT; ++i) {
+    DCHECK(!g_browser_threads[i]) <<
+        "Threads must be listed in the reverse order that they die";
+  }
+#endif
+}
+
 // static
 bool BrowserThread::IsWellKnownThread(ID identifier) {
   base::AutoLock lock(g_lock.Get());
@@ -394,23 +393,4 @@
   return proxy;
 }
 
-base::Thread* BrowserThread::UnsafeGetBrowserThread(ID identifier) {
-  base::AutoLock lock(g_lock.Get());
-  base::Thread* thread = g_browser_threads[identifier];
-  DCHECK(thread);
-  return thread;
-}
-
-void BrowserThread::SetDelegate(ID identifier,
-                                BrowserThreadDelegate* delegate) {
-  using base::subtle::AtomicWord;
-  AtomicWord* storage = reinterpret_cast<AtomicWord*>(
-      &g_browser_thread_delegates[identifier]);
-  AtomicWord old_pointer = base::subtle::NoBarrier_AtomicExchange(
-      storage, reinterpret_cast<AtomicWord>(delegate));
-
-  // This catches registration when previously registered.
-  DCHECK(!delegate || !old_pointer);
-}
-
 }  // namespace content