android: Java-based launcher thread

content/public/android/java/src/org/chromium/content/browser/LauncherThread.java

Index: content/public/android/java/src/org/chromium/content/browser/LauncherThread.java
diff --git a/content/public/android/java/src/org/chromium/content/browser/LauncherThread.java b/content/public/android/java/src/org/chromium/content/browser/LauncherThread.java
new file mode 100644
index 0000000000000000000000000000000000000000..2f3077690546d3819ffd04d913fff8a649a3b416
--- /dev/null
+++ b/content/public/android/java/src/org/chromium/content/browser/LauncherThread.java
@@ -0,0 +1,44 @@
+// Copyright 2017 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.
+
+package org.chromium.content.browser;
+
+import android.os.Handler;
+
+import org.chromium.base.JavaHandlerThread;
+import org.chromium.base.annotations.CalledByNative;
+import org.chromium.base.annotations.JNINamespace;
+
+@JNINamespace("content::android")
+class LauncherThread {
+    private static final Object sInstanceLock = new Object();
+    private static LauncherThread sInstance;
+
+    static LauncherThread getInstance() {
+        synchronized (sInstanceLock) {

[agrieve, 2017/03/28 19:59:32]

There's no reason to use this class without creating the singleton, so it would
be simpler to just have:

private static LauncherThread sInstance = new LauncherThread()

Going even further, there's are no non-static methods here, so you might as well
just avoid the object altogether and do:

private static final sThread = ...
private static final sHandler = ...
static {
  sThread.maybeStart();
}

[boliu, 2017/03/28 23:30:52]

Done.

+            if (sInstance == null) {
+                sInstance = new LauncherThread();
+            }
+        }
+        return sInstance;
+    }
+
+    static void post(Runnable r) {
+        getInstance().mHandler.post(r);
+    }
+
+    @CalledByNative
+    private static JavaHandlerThread getHandlerThread() {
+        return getInstance().mThread;
+    }
+
+    private final JavaHandlerThread mThread;
+    private final Handler mHandler;
+
+    private LauncherThread() {
+        mThread = new JavaHandlerThread("Chrome_ProcessLauncherThread");
+        mThread.maybeStart();
+        mHandler = new Handler(mThread.getLooper());
+    }
+}