Refactoring ChildProcessConnection.

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 android.os.Looper;
 
 import org.chromium.base.JavaHandlerThread;
+import org.chromium.base.VisibleForTesting;
 import org.chromium.base.annotations.CalledByNative;
 import org.chromium.base.annotations.JNINamespace;
 
 /** This is BrowserThread::PROCESS_LAUNCHER. It is available before native library is loaded. */
 @JNINamespace("content::android")
 public final class LauncherThread {
     private static final JavaHandlerThread sThread =
             new JavaHandlerThread("Chrome_ProcessLauncherThread");
-    private static final Handler sHandler;
+    private static final Handler sThreadHandler;
+    // Can be overritten in tests.
+    private static Handler sHandler;
     static {
         sThread.maybeStart();
-        sHandler = new Handler(sThread.getLooper());
+        sThreadHandler = new Handler(sThread.getLooper());
+        sHandler = sThreadHandler;
     }
 
     public static void post(Runnable r) {
         sHandler.post(r);
     }
 
     public static void postDelayed(Runnable r, long delayMillis) {
         sHandler.postDelayed(r, delayMillis);
     }
 
     public static boolean runningOnLauncherThread() {
         return sHandler.getLooper() == Looper.myLooper();
     }
 
+    @VisibleForTesting
+    public static void setCurrentThreadAsLauncherThread() {
+        sHandler = new Handler();
+    }
+
+    @VisibleForTesting
+    public static void setLauncherThreadAsLauncherThread() {
+        sHandler = sThreadHandler;
+    }
+
     @CalledByNative
     private static JavaHandlerThread getHandlerThread() {
         return sThread;
     }
 
     private LauncherThread() {}
 }