Add AccessibilityManager#removeClient

Whenever an app makes a Text toast, this gets routed through systemUI
starting from R. Two A11yManagerClients are registered with
A11yManagerService for every toast. Since clients aren't removed until
the process is killed, there are a bunch of clients from systemui
hanging around and potentially cause the system to crash.

We add a way here to explicitly unregister a client

Test: build and flash,
atest android.view.accessibility.AccessibilityManagerTest
Bug: 189010828

Change-Id: I3f71bac475b4539c7be5b328adeb0be35a0b5543

core/java/android/view/accessibility/AccessibilityManager.java

@@ -516,6 +516,25 @@ public final class AccessibilityManager {
         return mClient;
     }
 
+    /**
+     * Unregisters the IAccessibilityManagerClient from the backing service
+     * @hide
+     */
+    public boolean removeClient() {
+        synchronized (mLock) {
+            IAccessibilityManager service = getServiceLocked();
+            if (service == null) {
+                return false;
+            }
+            try {
+                return service.removeClient(mClient, mUserId);
+            } catch (RemoteException re) {
+                Log.e(LOG_TAG, "AccessibilityManagerService is dead", re);
+            }
+        }
+        return false;
+    }
+
     /**
      * @hide
      */

core/java/android/view/accessibility/IAccessibilityManager.aidl

@@ -42,6 +42,8 @@ interface IAccessibilityManager {
 
     long addClient(IAccessibilityManagerClient client, int userId);
 
+    boolean removeClient(IAccessibilityManagerClient client, int userId);
+
     List<AccessibilityServiceInfo> getInstalledAccessibilityServiceList(int userId);
 
     @UnsupportedAppUsage(maxTargetSdk = 30, trackingBug = 170729553)

core/tests/coretests/src/android/view/accessibility/AccessibilityManagerTest.java

@@ -115,6 +115,13 @@ public class AccessibilityManagerTest {
         return manager;
     }
 
+    @Test
+    public void testRemoveManager() throws Exception {
+        AccessibilityManager manager = createManager(WITH_A11Y_ENABLED);
+        manager.removeClient();
+        verify(mMockService).removeClient(manager.getClient(), UserHandle.USER_CURRENT);
+    }
+
     @Test
     public void testGetAccessibilityServiceList() throws Exception {
         // create a list of installed accessibility services the mock service returns

services/accessibility/java/com/android/server/accessibility/AccessibilityManagerService.java

@@ -709,6 +709,34 @@ public class AccessibilityManagerService extends IAccessibilityManager.Stub
         }
     }
 
+    @Override
+    public boolean removeClient(IAccessibilityManagerClient callback, int userId) {
+        // TODO(b/190216606): Add tracing for removeClient when implementation is the same in master
+
+        synchronized (mLock) {
+            final int resolvedUserId = mSecurityPolicy
+                    .resolveCallingUserIdEnforcingPermissionsLocked(userId);
+
+            AccessibilityUserState userState = getUserStateLocked(resolvedUserId);
+            if (mSecurityPolicy.isCallerInteractingAcrossUsers(userId)) {
+                boolean unregistered = mGlobalClients.unregister(callback);
+                if (DEBUG) {
+                    Slog.i(LOG_TAG,
+                            "Removed global client for pid:" + Binder.getCallingPid() + "state: "
+                                    + unregistered);
+                }
+                return unregistered;
+            } else {
+                boolean unregistered = userState.mUserClients.unregister(callback);
+                if (DEBUG) {
+                    Slog.i(LOG_TAG, "Removed user client for pid:" + Binder.getCallingPid()
+                            + " and userId:" + resolvedUserId + "state: " + unregistered);
+                }
+                return unregistered;
+            }
+        }
+    }
+
     @Override
     public void sendAccessibilityEvent(AccessibilityEvent event, int userId) {
         if (mTraceManager.isA11yTracingEnabled()) {
@@ -3271,6 +3299,14 @@ public class AccessibilityManagerService extends IAccessibilityManager.Stub
                 pw.println();
             }
             mA11yWindowManager.dump(fd, pw, args);
+            pw.println("Global client list info:{");
+            mGlobalClients.dump(pw, "    Client list ");
+            pw.println("    Registered clients:{");
+            for (int i = 0; i < mGlobalClients.getRegisteredCallbackCount(); i++) {
+                AccessibilityManagerService.Client client = (AccessibilityManagerService.Client)
+                        mGlobalClients.getRegisteredCallbackCookie(i);
+                pw.append(Arrays.toString(client.mPackageNames));
+            }
         }
     }
 

services/accessibility/java/com/android/server/accessibility/AccessibilityUserState.java

@@ -51,6 +51,7 @@ import com.android.internal.accessibility.AccessibilityShortcutController;
 import java.io.FileDescriptor;
 import java.io.PrintWriter;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Collection;
 import java.util.HashMap;
 import java.util.HashSet;
@@ -573,6 +574,15 @@ class AccessibilityUserState {
                 pw.append(componentName.toShortString());
             }
         }
+        pw.println("}");
+        pw.println("     Client list info:{");
+        mUserClients.dump(pw, "          Client list ");
+        pw.println("          Registered clients:{");
+        for (int i = 0; i < mUserClients.getRegisteredCallbackCount(); i++) {
+            AccessibilityManagerService.Client client = (AccessibilityManagerService.Client)
+                    mUserClients.getRegisteredCallbackCookie(i);
+            pw.append(Arrays.toString(client.mPackageNames));
+        }
         pw.println("}]");
     }