InputManager: Expose pilferPointers API

We can only migrate existing gesture monitors to spy windows if we allow
pilfering from these spy windows. Expose the pilferPointers API so that
other processes can pilfer from arbitrary input windows.

The pilferPointers API is guarded with the MONITOR_INPUT signature
permission.

Bug: 257977069
Test: Build
Change-Id: Ice43ed420502ce3b5e5d37d9ac9e810a51ed07bc

core/java/android/hardware/input/IInputManager.aidl

@@ -168,4 +168,9 @@ interface IInputManager {
     @JavaPassthrough(annotation="@android.annotation.RequiresPermission(value = "
             + "android.Manifest.permission.BLUETOOTH)")
     String getInputDeviceBluetoothAddress(int deviceId);
+
+    @EnforcePermission("MONITOR_INPUT")
+    @JavaPassthrough(annotation="@android.annotation.RequiresPermission(value = "
+            + "android.Manifest.permission.MONITOR_INPUT)")
+    void pilferPointers(IBinder inputChannelToken);
 }

core/java/android/hardware/input/InputManager.java

@@ -1719,6 +1719,34 @@ public final class InputManager {
         }
     }
 
+    /**
+     * Pilfer pointers from an input channel.
+     *
+     * Takes all the current pointer event streams that are currently being sent to the given
+     * input channel and generates appropriate cancellations for all other windows that are
+     * receiving these pointers.
+     *
+     * This API is intended to be used in conjunction with spy windows. When a spy window pilfers
+     * pointers, the foreground windows and all other spy windows that are receiving any of the
+     * pointers that are currently being dispatched to the pilfering window will have those pointers
+     * canceled. Only the pilfering window will continue to receive events for the affected pointers
+     * until the pointer is lifted.
+     *
+     * This method should be used with caution as unexpected pilfering can break fundamental user
+     * interactions.
+     *
+     * @see android.os.InputConfig#SPY
+     * @hide
+     */
+    @RequiresPermission(Manifest.permission.MONITOR_INPUT)
+    public void pilferPointers(IBinder inputChannelToken) {
+        try {
+            mIm.pilferPointers(inputChannelToken);
+        } catch (RemoteException e) {
+            throw e.rethrowFromSystemServer();
+        }
+    }
+
     /**
      * Adds a battery listener to be notified about {@link BatteryState} changes for an input
      * device. The same listener can be registered for multiple input devices.

services/core/java/com/android/server/input/InputManagerService.java

@@ -2679,6 +2679,13 @@ public class InputManagerService extends IInputManager.Stub
         return mNative.getBluetoothAddress(deviceId);
     }
 
+    @EnforcePermission(Manifest.permission.MONITOR_INPUT)
+    @Override
+    public void pilferPointers(IBinder inputChannelToken) {
+        Objects.requireNonNull(inputChannelToken);
+        mNative.pilferPointers(inputChannelToken);
+    }
+
     @Override
     public void dump(FileDescriptor fd, PrintWriter pw, String[] args) {
         if (!DumpUtils.checkDumpPermission(mContext, TAG, pw)) return;