Android content_browsertests: Allow processing java tasks in nested mode.

content/shell/android/browsertests_apk/src/org/chromium/content_browsertests_apk/BrowserTestSystemMessageHandler.java

Index: content/shell/android/browsertests_apk/src/org/chromium/content_browsertests_apk/BrowserTestSystemMessageHandler.java
diff --git a/content/shell/android/browsertests_apk/src/org/chromium/content_browsertests_apk/BrowserTestSystemMessageHandler.java b/content/shell/android/browsertests_apk/src/org/chromium/content_browsertests_apk/BrowserTestSystemMessageHandler.java
new file mode 100644
index 0000000000000000000000000000000000000000..2ba7e9435c86bc67615bda67095797f6d32b4551
--- /dev/null
+++ b/content/shell/android/browsertests_apk/src/org/chromium/content_browsertests_apk/BrowserTestSystemMessageHandler.java
@@ -0,0 +1,128 @@
+// 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.
+
+package org.chromium.content_browsertests_apk;
+
+import android.os.Handler;
+import android.os.Looper;
+import android.os.Message;
+import android.os.MessageQueue;
+import android.util.Log;
+
+import org.chromium.base.CalledByNative;
+import org.chromium.base.JNINamespace;
+import java.lang.reflect.Method;
+import java.lang.reflect.Field;
+import java.lang.reflect.InvocationTargetException;
+
+/**
+ * Handles processing messages in nested run loops.
+ *
+ * Android does not support nested message loops by default. While running
+ * in nested mode, we use reflection to retreive messages from the MessageQueue
+ * and dispatch them.
+ */
+@JNINamespace("content")
+class BrowserTestSystemMessageHandler {
+    // See org.chromium.base.SystemMessageHandler for more message ids.
+    // The id here should not conflict with the ones in SystemMessageHandler.
+    private static final int QUIT_MESSAGE = 10;
+    private static final Handler mHandler = new Handler();
+
+    private BrowserTestSystemMessageHandler() {
+    }
+
+    /**
+     * Processes messages from the current MessageQueue till the queue becomes idle.
+     */
+    @SuppressWarnings("unused")
+    @CalledByNative
+    private boolean runNestedLoopTillIdle() {
+        boolean quitLoop = false;
+
+        MessageQueue queue = Looper.myQueue();
+        queue.addIdleHandler(new MessageQueue.IdleHandler() {
+            @Override
+            public boolean queueIdle() {
+                mHandler.sendMessage(mHandler.obtainMessage(QUIT_MESSAGE));
+                return false;
+            }
+        });
+
+        Class<?> messageQueueClazz = queue.getClass();
+        Method nextMethod = null;
+        try {
+            nextMethod = messageQueueClazz.getDeclaredMethod("next");
+        } catch (SecurityException e) {
+            e.printStackTrace();
+            return false;
+        } catch (NoSuchMethodException e) {
+            e.printStackTrace();
+            return false;
+        }
+        nextMethod.setAccessible(true);
+
+        while (!quitLoop) {
+            Message msg = null;
+            try {
+                msg = (Message)nextMethod.invoke(queue);
+            } catch (IllegalArgumentException e) {
+                e.printStackTrace();
+                return false;
+            } catch (IllegalAccessException e) {
+                e.printStackTrace();
+                return false;
+            } catch (InvocationTargetException e) {
+                e.printStackTrace();
+                return false;
+            }
+
+            if (msg != null) {
+                if (msg.what == QUIT_MESSAGE) {
+                    quitLoop = true;
+                }
+                Class messageClazz = msg.getClass();
+                Field targetFiled = null;
+                try {
+                    targetFiled = messageClazz.getDeclaredField("target");
+                } catch (SecurityException e) {
+                    e.printStackTrace();
+                    return false;
+                } catch (NoSuchFieldException e) {
+                    e.printStackTrace();
+                    return false;
+                }
+                targetFiled.setAccessible(true);
+
+                Handler target = null;
+                try {
+                    target = (Handler) targetFiled.get(msg);
+                } catch (IllegalArgumentException e) {
+                    e.printStackTrace();
+                    return false;
+                } catch (IllegalAccessException e) {
+                    e.printStackTrace();
+                    return false;
+                }
+
+                if (target == null) {
+                    // No target is a magic identifier for the quit message.
+                    quitLoop = true;
+                }
+
+                target.dispatchMessage(msg);
+                msg.recycle();
+            } else {
+                quitLoop = true;
+            }
+        }
+        return true;
+    }
+
+    @SuppressWarnings("unused")
+    @CalledByNative
+    private static BrowserTestSystemMessageHandler create() {
+        return new BrowserTestSystemMessageHandler();
+    }
+}