Let A11yIME use its own IPC definitions

This is a follow up CL to our previuos CL [1], which enabled
AccessibilityService to use a subset of InputConnection APIs.

In that CL we have reused existing AIDL interfaces that were designed
and maintained for IMEs for simplicity, where a non trivial amount of
unnecessary IPC endpoints were included.

From the security and maintainability viewpoints, however, exposing
unnecessary IPC endpoints is discouraged in general.  To address such
concerns this CL introduces a set of dedicated IPC definitions for
A11yIME so that we do not need to reuse IPCs for IMEs.

This CL also stops passing InputBinding object to A11yIME process as
it contains IInputContext Binder Proxy, which can still be used to
directly invoke fallback InputConnection.  This is doable now because
A11yIME no longer relies on fallback InputConnection [2].

This CL is should not have any observable changes in the semantics.
End-to-end CTS tests guarantee that everything is still working as
intended now and in the future.

 [1]: Ia651a811093a939d00c081be1961e24ed3ad0356
      fb17e5ae7a9e1a095d114d8dde76f14578b6c233
 [2]: I2af3cd50444d8ddf25aa0f6479238156914e6fff
      dc635efb687ac04045f2756b02c5ca2435762956

Fix: 215633021
Fix: 215636776
Test: atest CtsInputMethodTestCases:AccessibilityInputMethodTest
Test: atest CtsAccessibilityServiceTestCases:AccessibilityInputConnectionTest
Test: atest CtsAccessibilityServiceTestCases:AccessibilityImeTest
Change-Id: I5ff2e804cbcf90828370a0612ff54111130bdff4

1 files changed, 116 insertions, 0 deletions

diff --git a/core/java/android/accessibilityservice/AccessibilityInputMethodSessionWrapper.java b/core/java/android/accessibilityservice/AccessibilityInputMethodSessionWrapper.java
new file mode 100644
index 000000000000..3252ab23486f
--- /dev/null
+++ b/core/java/android/accessibilityservice/AccessibilityInputMethodSessionWrapper.java
@@ -0,0 +1,116 @@
+/*
+ * Copyright (C) 2022 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package android.accessibilityservice;
+
+import android.annotation.AnyThread;
+import android.annotation.NonNull;
+import android.annotation.Nullable;
+import android.os.Handler;
+import android.os.Looper;
+import android.view.inputmethod.EditorInfo;
+
+import com.android.internal.inputmethod.IAccessibilityInputMethodSession;
+import com.android.internal.inputmethod.IRemoteAccessibilityInputConnection;
+
+import java.util.concurrent.atomic.AtomicReference;
+
+final class AccessibilityInputMethodSessionWrapper extends IAccessibilityInputMethodSession.Stub {
+    private final Handler mHandler;
+
+    @NonNull
+    private final AtomicReference<AccessibilityInputMethodSession> mSessionRef;
+
+    AccessibilityInputMethodSessionWrapper(
+            @NonNull Looper looper, @NonNull AccessibilityInputMethodSession session) {
+        mSessionRef = new AtomicReference<>(session);
+        mHandler = Handler.createAsync(looper);
+    }
+
+    @AnyThread
+    @Nullable
+    AccessibilityInputMethodSession getSession() {
+        return mSessionRef.get();
+    }
+
+    @Override
+    public void updateSelection(int oldSelStart, int oldSelEnd,
+            int newSelStart, int newSelEnd, int candidatesStart, int candidatesEnd) {
+        if (mHandler.getLooper().isCurrentThread()) {
+            doUpdateSelection(oldSelStart, oldSelEnd, newSelStart, newSelEnd, candidatesStart,
+                    candidatesEnd);
+        } else {
+            mHandler.post(() -> doUpdateSelection(oldSelStart, oldSelEnd, newSelStart,
+                    newSelEnd, candidatesStart, candidatesEnd));
+        }
+    }
+
+    private void doUpdateSelection(int oldSelStart, int oldSelEnd,
+            int newSelStart, int newSelEnd, int candidatesStart, int candidatesEnd) {
+        final AccessibilityInputMethodSession session = mSessionRef.get();
+        if (session != null) {
+            session.updateSelection(oldSelStart, oldSelEnd, newSelStart, newSelEnd, candidatesStart,
+                    candidatesEnd);
+        }
+    }
+
+    @Override
+    public void finishInput() {
+        if (mHandler.getLooper().isCurrentThread()) {
+            doFinishInput();
+        } else {
+            mHandler.post(this::doFinishInput);
+        }
+    }
+
+    private void doFinishInput() {
+        final AccessibilityInputMethodSession session = mSessionRef.get();
+        if (session != null) {
+            session.finishInput();
+        }
+    }
+
+    @Override
+    public void finishSession() {
+        if (mHandler.getLooper().isCurrentThread()) {
+            doFinishSession();
+        } else {
+            mHandler.post(this::doFinishSession);
+        }
+    }
+
+    private void doFinishSession() {
+        mSessionRef.set(null);
+    }
+
+    @Override
+    public void invalidateInput(EditorInfo editorInfo,
+            IRemoteAccessibilityInputConnection connection, int sessionId) {
+        if (mHandler.getLooper().isCurrentThread()) {
+            doInvalidateInput(editorInfo, connection, sessionId);
+        } else {
+            mHandler.post(() -> doInvalidateInput(editorInfo, connection, sessionId));
+        }
+    }
+
+    private void doInvalidateInput(EditorInfo editorInfo,
+            IRemoteAccessibilityInputConnection connection, int sessionId) {
+        final AccessibilityInputMethodSession session = mSessionRef.get();
+        if (session != null) {
+            session.invalidateInput(editorInfo, connection, sessionId);
+        }
+    }
+}