Making a way to create thread with a Java Looper for Android

base/android/java_thread.cc

+// Copyright (c) 2013 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 "base/android/java_thread.h"
+
+#include <jni.h>
+
+#include "base/android/jni_android.h"
+#include "base/android/jni_string.h"
+#include "base/message_loop.h"
+#include "base/synchronization/waitable_event.h"
+#include "jni/JavaThread_jni.h"
+
+namespace base {
+
+namespace android {
+
+JavaThread::JavaThread(const char* name)
+    : started_(false) {
+  JNIEnv* env = base::android::AttachCurrentThread();
+
+  java_thread_.Reset(Java_JavaThread_create(
+      env, ConvertUTF8ToJavaString(env, name).Release()));
+}
+
+void JavaThread::Start() {
+  // Check the thread has not already been started.
+  DCHECK(!started_);
+
+  JNIEnv* env = base::android::AttachCurrentThread();
+  base::WaitableEvent initialize_event(false, false);
+  Java_JavaThread_start(env,
+                        java_thread_.obj(),
+                        reinterpret_cast<jint>(this),
+                        reinterpret_cast<jint>(&initialize_event));
+  // Wait for thread to be initialized so it is ready to be used when Start
+  // returns.
+  initialize_event.Wait();
+
+  // Delete object only used in initialization.

[benm (inactive), 2013/07/17 10:52:29]

nit, don't think this comment makes sense anymore?

[Kristian Monsen, 2013/07/17 21:02:37]

Done.

+  started_ = true;
+}
+
+void JavaThread::Stop() {
+}
+
+void JavaThread::InitializeThread(JNIEnv* env, jobject obj, jint event) {
+  // TYPE_UI to get the Android java style message loop.
+  message_loop_.reset(new base::MessageLoop(base::MessageLoop::TYPE_UI));
+  MessageLoopForUI::current()->Start();

[joth, 2013/07/17 16:29:18]

So if message_loop_ was of type MessageLoopForUI you could then do
message_loop_->Start()  ?

[Kristian Monsen, 2013/07/17 21:02:37]

Yeah ...
But we call the MessageLoop CTOR, and clank does it the same way:
https://code.google.com/p/chromium/codesearch#chromium/src/chrome/browser/chr...

Sorry if I am not super responsive to the suggestions, and do agree it is not
super great as is, but I think it is better than casting it and changing the
type to MesageLoopUI. I would mostly like to just remove that Start method.

+  reinterpret_cast<base::WaitableEvent*>(event)->Signal();
+}
+
+// static
+bool JavaThread::RegisterBindings(JNIEnv* env) {
+  return RegisterNativesImpl(env);
+}
+
+} // namespace android
+
+} // namespace base