Introduce ThreadedInputConnection behind a switch

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

+// 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.os.Handler;
+import android.os.HandlerThread;
+import android.view.View;
+import android.view.inputmethod.EditorInfo;
+
+import org.chromium.base.Log;
+import org.chromium.base.VisibleForTesting;
+
+/**
+ * A factory class for {@link ThreadedInputConnection}. The class also includes triggering
+ * mechanism (hack) to run our InputConnection on non-UI thread.
+ */
+// TODO(changwan): add unit tests once Robolectric supports Android API level >= 21.
+// See crbug.com/588547 for details.
+public class ThreadedInputConnectionFactory implements ChromiumBaseInputConnection.Factory {
+    private static final String TAG = "cr_Ime";
+    private static final boolean DEBUG_LOGS = false;
+
+    private final Handler mHandler;
+    private final InputMethodManagerWrapper mInputMethodManagerWrapper;
+    private final InputMethodUma mInputMethodUma;
+    private ThreadedInputConnectionProxyView mProxyView;
+    private ThreadedInputConnection mThreadedInputConnection;
+
+    ThreadedInputConnectionFactory(
+            InputMethodManagerWrapper inputMethodManagerWrapper) {
+        mInputMethodManagerWrapper = inputMethodManagerWrapper;
+        mHandler = createHandler();
+        mInputMethodUma = createInputMethodUma();
+    }
+
+    @VisibleForTesting
+    protected Handler createHandler() {
+        HandlerThread thread =
+                new HandlerThread("InputConnectionHandlerThread", HandlerThread.NORM_PRIORITY);
+        thread.start();
+        return new Handler(thread.getLooper());
+    }
+
+    @VisibleForTesting
+    protected ThreadedInputConnectionProxyView createProxyView(
+            Handler handler, View containerView) {
+        return new ThreadedInputConnectionProxyView(
+                containerView.getContext(), handler, containerView);
+    }
+
+    @VisibleForTesting
+    protected InputMethodUma createInputMethodUma() {
+        return new InputMethodUma();
+    }
+
+    private boolean shouldTriggerDelayedOnCreateInputConnection() {
+        // Note that ThreadedInputConnectionProxyView intentionally calls
+        // View#onCreateInputConnection() and not a separate method in this class.
+        // There are third party apps that override WebView#onCreateInputConnection(),
+        // and we still want to call them for consistency. The setback here is that the only
+        // way to distinguish calls from InputMethodManager and from ProxyView is by looking at
+        // the call stack.
+        for (StackTraceElement ste : Thread.currentThread().getStackTrace()) {
+            String className = ste.getClassName();
+            if (className != null
+                    && (className.contains(ThreadedInputConnectionProxyView.class.getName())
+                    || className.contains("TestInputMethodManagerWrapper"))) {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    @Override
+    public ThreadedInputConnection initializeAndGet(
+            View view, ImeAdapter imeAdapter, int inputType, int inputFlags, int selectionStart,
+            int selectionEnd, EditorInfo outAttrs) {
+        ImeUtils.checkOnUiThread();
+        if (shouldTriggerDelayedOnCreateInputConnection()) {
+            triggerDelayedOnCreateInputConnection(view);
+            return null;
+        }
+        if (DEBUG_LOGS) Log.w(TAG, "initializeAndGet: called from proxy view");
+        if (mThreadedInputConnection == null) {
+            if (DEBUG_LOGS) Log.w(TAG, "Creating ThreadedInputConnection...");
+            mThreadedInputConnection = new ThreadedInputConnection(imeAdapter, mHandler);
+        }
+        mThreadedInputConnection.initializeOutAttrsOnUiThread(inputType, inputFlags,
+                selectionStart, selectionEnd, outAttrs);
+        return mThreadedInputConnection;
+    }
+
+    private void triggerDelayedOnCreateInputConnection(final View view) {
+        if (DEBUG_LOGS) Log.w(TAG, "triggerDelayedOnCreateInputConnection");
+        if (mProxyView == null) {
+            mProxyView = createProxyView(mHandler, view);
+        }
+        mProxyView.requestFocus();
+        view.getHandler().post(new Runnable() {
+            @Override
+            public void run() {
+                // This is a hack to make InputMethodManager believe that the proxy view
+                // now has a focus. As a result, InputMethodManager will think that mProxyView
+                // is focused, and will call getHandler() of the view when creating input
+                // connection.
+
+                // Step 1: Set mProxyView as InputMethodManager#mNextServedView.
+                mProxyView.onWindowFocusChanged(true);
+
+                // Step 2: Have InputMethodManager focus in on mNextServedView.
+                // As a result, IMM will call onCreateInputConnection() on mProxyView on the same
+                // thread as mProxyView.getHandler(). It will also call subsequent InputConnection
+                // methods on this IME thread.
+                mInputMethodManagerWrapper.isActive(view);
+
+                // Step 3: Check that the above hack worked.
+                mHandler.post(new Runnable() {
+                    @Override
+                    public void run() {
+                        // Some other view already took focus. Container view should be active
+                        // otherwise regardless of whether proxy view is registered or not.
+                        if (!mInputMethodManagerWrapper.isActive(view)) return;
+
+                        // Success.
+                        if (mInputMethodManagerWrapper.isActive(mProxyView)) {
+                            mInputMethodUma.recordProxyViewSuccess();
+                            return;
+                        }
+
+                        if (mThreadedInputConnection == null) {
+                            // First time and failed. It is highly likely that this does not work
+                            // systematically.
+                            mInputMethodUma.recordProxyViewFailure();
+                            onRegisterProxyViewFailed();
+                        } else {
+                            // Most likely that we already lost view focus.
+                            mInputMethodUma.recordProxyViewDetectionFailure();
+                        }
+                    }
+                });
+            }
+        });
+    }
+
+    @VisibleForTesting
+    protected void onRegisterProxyViewFailed() {
+        throw new AssertionError("Failed to register proxy view");
+    }
+
+    @Override
+    public Handler getHandler() {
+        return mHandler;
+    }
+}