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

ppapi/examples/threading/threading.cc

+// 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/c/pp_errors.h"
+#include "ppapi/cpp/input_event.h"
+#include "ppapi/cpp/instance.h"
+#include "ppapi/cpp/module.h"
+#include "ppapi/utility/completion_callback_factory.h"
+#include "ppapi/utility/threading/simple_thread.h"
+
+class MyInstance : public pp::Instance {
+ public:
+  MyInstance(PP_Instance instance) : pp::Instance(instance) {
+    thread_ = new pp::SimpleThread(this);
+    factory_.Initialize(this);
+    RequestInputEvents(PP_INPUTEVENT_CLASS_MOUSE);

[bbudge, 2012/01/25 00:35:26]

Would it work if this was moved to Init()? It seems out of place here.

+  }
+
+  virtual ~MyInstance() {
+    delete thread_;
+  }
+
+  virtual bool Init(uint32_t argc, const char* argn[], const char* argv[]) {
+    thread_->Start();
+    thread_->message_loop().PostWork(
+        factory_.NewCallback(&MyInstance::CallOnBackground));
+    return true;
+  }
+
+  virtual bool HandleInputEvent(const pp::InputEvent& event) {
+    switch (event.GetType()) {
+      case PP_INPUTEVENT_TYPE_MOUSEDOWN:
+        return true;
+      case PP_INPUTEVENT_TYPE_MOUSEMOVE:
+        return true;
+      case PP_INPUTEVENT_TYPE_KEYDOWN:
+        return true;
+      default:
+        return false;
+    }
+  }
+
+  virtual void DidChangeView(const pp::View& view) {
+  }
+
+ private:
+  void CallOnBackground(int32_t result) {
+  }
+
+  pp::CompletionCallbackFactory<MyInstance> factory_;
+
+  pp::SimpleThread* thread_;
+};
+
+
+class MyModule : public pp::Module {
+ public:
+  MyModule() : pp::Module() {}
+  virtual ~MyModule() {}
+
+  virtual pp::Instance* CreateInstance(PP_Instance instance) {
+    return new MyInstance(instance);
+  }
+};
+
+namespace pp {
+
+// Factory function for your specialization of the Module object.
+Module* CreateModule() {
+  return new MyModule();
+}
+
+}  // namespace pp