First pass at implementing the MessageLoop interface. This includes a simple

ppapi/utility/threading/simple_thread.cc

Index: ppapi/utility/threading/simple_thread.cc
diff --git a/ppapi/utility/threading/simple_thread.cc b/ppapi/utility/threading/simple_thread.cc
new file mode 100644
index 0000000000000000000000000000000000000000..ff2ccd462da6e2ca499e26d53a3103010692cf5a
--- /dev/null
+++ b/ppapi/utility/threading/simple_thread.cc
@@ -0,0 +1,92 @@
+// 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 "ppapi/utility/threading/simple_thread.h"
+
+namespace pp {
+
+namespace {
+
+struct ThreadData {
+  MessageLoop_Dev message_loop;
+
+  SimpleThread::ThreadFunc func;
+  void* user_data;
+};
+
+#ifdef WIN32
+DWORD WINAPI RunThread(void* void_data) {
+#else
+void* RunThread(void* void_data) {
+#endif
+  ThreadData* data = static_cast<ThreadData*>(void_data);
+  data->message_loop.AttachToCurrentThread();
+
+  if (data->func)
+    data->func(data->message_loop, data->user_data);
+  else
+    data->message_loop.Run();
+
+  delete data;
+  return NULL;
+}
+
+}   // namespace
+
+SimpleThread::SimpleThread(Instance* instance)
+    : instance_(instance),
+      message_loop_(instance),
+      thread_(0) {
+}
+
+SimpleThread::~SimpleThread() {
+  Join();
+}
+
+bool SimpleThread::Start() {
+  return StartWithFunction(NULL, NULL);
+}
+
+bool SimpleThread::Join() {
+  if (!thread_)
+    return false;
+
+  message_loop_.PostQuit(true);
+
+#ifdef WIN32
+  DWORD result = WaitForSingleObject(thread_, INFINITE);
+  CloseHandle(thread_);
+  thread_ = 0;
+  return result == WAIT_OBJECT_0;
+
+#else
+  void* retval;
+  int result = pthread_join(thread_, &retval);
+  thread_ = 0;
+  return result == 0;
+#endif
+}
+
+bool SimpleThread::StartWithFunction(ThreadFunc func, void* user_data) {
+  if (thread_)
+    return false;
+
+  ThreadData* data = new ThreadData;
+  data->message_loop = message_loop_;
+  data->func = func;
+  data->user_data = user_data;
+
+#ifdef WIN32
+  thread_ = CreateThread(NULL, 0, &RunThread, data, NULL);
+  if (!thread_) {
+#else
+  if (pthread_create(&thread_, NULL, &RunThread, data) != 0) {
+#endif
+    delete data;
+    return false;
+  }
+  return true;
+}
+
+}  // namespace pp