android: Java-based launcher thread

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

+// 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")
+final class LauncherThread {
+    private static final JavaHandlerThread sThread =
+            new JavaHandlerThread("Chrome_ProcessLauncherThread");
+    private static final Handler sHandler;
+    static {
+        sThread.maybeStart();
+        sHandler = new Handler(sThread.getLooper());
+    }
+
+    static void post(Runnable r) {
+        sHandler.post(r);
+    }
+
+    @CalledByNative
+    private static JavaHandlerThread getHandlerThread() {
+        return sThread;
+    }
+
+    private LauncherThread() {}
+}