Introduce ThreadedInputConnection behind a switch

content/public/android/java/src/org/chromium/content/browser/input/ChromiumInputConnectionFactory.java

Index: content/public/android/java/src/org/chromium/content/browser/input/ChromiumInputConnectionFactory.java
diff --git a/content/public/android/java/src/org/chromium/content/browser/input/ChromiumInputConnectionFactory.java b/content/public/android/java/src/org/chromium/content/browser/input/ChromiumInputConnectionFactory.java
new file mode 100644
index 0000000000000000000000000000000000000000..cb29b82fbb6650d640b5711fd5ef7220bf825050
--- /dev/null
+++ b/content/public/android/java/src/org/chromium/content/browser/input/ChromiumInputConnectionFactory.java
@@ -0,0 +1,168 @@
+// Copyright 2016 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.input;
+
+import android.content.Context;
+import android.os.Handler;
+import android.os.HandlerThread;
+import android.os.Looper;
+import android.os.Message;
+import android.os.MessageQueue;
+import android.view.View;
+import android.view.inputmethod.EditorInfo;
+import android.view.inputmethod.InputMethodManager;
+
+import org.chromium.base.Log;
+import org.chromium.content.browser.input.ChromiumBaseInputConnection.ThreadManager;
+
+import java.lang.reflect.Constructor;
+import java.lang.reflect.Field;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+
+/**
+ * Default factory for ChromiumBaseInputConnection classes.
+ */
+public class ChromiumInputConnectionFactory implements ChromiumBaseInputConnection.Factory {
+    private static final String TAG = "cr_Ime";
+
+    private ChromiumInputConnection mChromiumInputConnection;
+    private final Handler mHandler;
+    private final ChromiumInputConnection.ThreadManager mThreadManager;
+
+    ChromiumInputConnectionFactory() {
+        HandlerThread thread =
+                new HandlerThread("InputConnectionHandlerThread", HandlerThread.NORM_PRIORITY);
+        thread.start();
+        mHandler = new Handler(thread.getLooper());
+        mThreadManager = new ThreadManager(mHandler);
+    }
+
+    @Override
+    public ChromiumBaseInputConnection initializeAndGet(View view, ImeAdapter imeAdapter,
+            int inputType, int inputFlags, EditorInfo outAttrs) {
+        ImeUtils.assertOnUiThread();
+        if (mChromiumInputConnection == null) {
+            Log.d(TAG, "Creating ChromiumInputConnection...");
+            mChromiumInputConnection = new ChromiumInputConnection(imeAdapter, mThreadManager);
+        }
+        mChromiumInputConnection.initializeOutAttrsOnUiThread(inputType, inputFlags, outAttrs);
+        switchInputConnectionLooper(view.getContext(), view.getHandler());
+        return mChromiumInputConnection;
+    }
+
+    @Override
+    public ThreadManager getThreadManager() {
+        return mThreadManager;
+    }
+
+    /**
+     * Pump messages from a handler and add them to another handler.
+     *
+     * @param sourceHandler The source handler.
+     * @param targetHandler The target handler.
+     * @throws NoSuchFieldException
+     * @throws IllegalAccessException
+     * @throws IllegalArgumentException
+     * @throws NoSuchMethodException
+     * @throws InvocationTargetException
+     */
+    private void pumpHandlerMessages(Handler sourceHandler, Handler targetHandler)
+            throws NoSuchFieldException, IllegalAccessException, IllegalArgumentException,
+                   NoSuchMethodException, InvocationTargetException {
+        Looper looper = sourceHandler.getLooper();
+        Method getQueueMethod = Looper.class.getDeclaredMethod("getQueue");
+        getQueueMethod.setAccessible(true);
+        MessageQueue queue = (MessageQueue) getQueueMethod.invoke(looper);
+        getQueueMethod.setAccessible(false);
+
+        Field messagesField = MessageQueue.class.getDeclaredField("mMessages");
+        Field nextField = Message.class.getDeclaredField("next");
+
+        synchronized (queue) {
+            // Copy messages first.
+            messagesField.setAccessible(true);
+            nextField.setAccessible(true);
+            Message msg = (Message) messagesField.get(queue);
+            while (msg != null) {
+                if (msg.getTarget() == sourceHandler) {
+                    Log.d(TAG, "Copying a message to the new handler...");
+                    Message newMsg = targetHandler.obtainMessage();
+                    newMsg.copyFrom(msg);
+                    targetHandler.sendMessage(newMsg);
+                }
+                msg = (Message) nextField.get(msg);
+            }
+            messagesField.setAccessible(false);
+            nextField.setAccessible(false);
+
+            // Now remove messages from the first handler.
+            sourceHandler.removeCallbacksAndMessages(null);
+        }
+    }
+
+    /**
+     * Switch the looper in InputMethodManager so that future calls to InputConnection
+     * can run in IME thread.
+     *
+     * @param context The context
+     * @param viewHandler The current handler for the View that this InputConnection will be
+     *                    attached to.
+     */
+    private void switchInputConnectionLooper(Context context, Handler viewHandler) {
+        Log.d(TAG, "switchInputConnectionLooper");
+        // Retrieve the same singleton instance of InputMethodManager that called
+        // onCreateInputConnection().
+        final InputMethodManager inputMethodManager =
+                (InputMethodManager) context.getSystemService(Context.INPUT_METHOD_SERVICE);
+        final Handler icHandler = mHandler;
+        viewHandler.post(new Runnable() {
+            @Override
+            public void run() {
+                Log.d(TAG, "switchInputConnectionLooper: replacing looper and handler");
+                try {
+                    // inputMethodManager.mServedInputConnectionWrapper.mMainLooper =
+                    // icHandler.getLooper();
+                    Field inputConnectionWrapperField = InputMethodManager.class.getDeclaredField(
+                            "mServedInputConnectionWrapper");
+                    inputConnectionWrapperField.setAccessible(true);
+                    Object inputConnectionWrapper =
+                            inputConnectionWrapperField.get(inputMethodManager);
+                    Class<?> iinputConnectionWrapperClass =
+                            Class.forName("com.android.internal.view.IInputConnectionWrapper");
+                    Field looperField =
+                            iinputConnectionWrapperClass.getDeclaredField("mMainLooper");
+                    looperField.setAccessible(true);
+                    looperField.set(inputConnectionWrapper, icHandler.getLooper());
+                    looperField.setAccessible(false);
+
+                    // inputMethodManager.mServedInputConnectionWrapper.mH =
+                    //         new IInputConnectionWrapper.MyHandler(icHandler.getLooper());
+                    Class<?> myHandlerClass = Class.forName(
+                            "com.android.internal.view.IInputConnectionWrapper$MyHandler");
+                    Constructor<?> ctor = myHandlerClass.getDeclaredConstructor(
+                            iinputConnectionWrapperClass, Looper.class);
+                    ctor.setAccessible(true);
+                    Handler myHandler = (Handler) ctor.newInstance(
+                            inputConnectionWrapper, icHandler.getLooper());
+                    Field handlerField = iinputConnectionWrapperClass.getDeclaredField("mH");
+                    ctor.setAccessible(false);
+                    handlerField.setAccessible(true);
+                    Handler oldHandler = (Handler) handlerField.get(inputConnectionWrapper);
+                    handlerField.set(inputConnectionWrapper, myHandler);
+                    handlerField.setAccessible(false);
+
+                    pumpHandlerMessages(oldHandler, myHandler);
+                } catch (IllegalAccessException | IllegalArgumentException | NoSuchFieldException
+                        | ClassNotFoundException | NoSuchMethodException | InstantiationException
+                        | InvocationTargetException | NullPointerException e) {
+                    e.printStackTrace();
+                    return;
+                }
+                Log.d(TAG, "switchInputConnectionLooper: replacing done.");
+            }
+        });
+    }
+}