Make TEST_INPUT_METHOD @TestAPI

This is a follow up CL to my previous CL [1], which introduced

  android.permission.TEST_INPUT_METHO

to protect several @TestApi methods in InputMethodManager.

This CL makes the permission itself as @TestApi so that it can be
included as an API constant in test-current.txt.  This also enables us
to minimize special permission while running CTS as follows.

  SystemUtil.runWithShellPermissionIdentity(() -> {
      // do something.
  }, Manifest.permission.TEST_INPUT_METHOD);

There must be no user observable behavior change in this CL.

 [1]: Ie79a3e9d41ce22605ae083594d639c37d08b7def
      b869c78380

Bug: 256239860
Test: presubmit
Change-Id: I1fd3ceda9a1b641e63c7633a223a9a806e78cd2d

core/api/test-current.txt

@@ -47,6 +47,7 @@ package android {
     field public static final String SET_KEYBOARD_LAYOUT = "android.permission.SET_KEYBOARD_LAYOUT";
     field public static final String SUSPEND_APPS = "android.permission.SUSPEND_APPS";
     field public static final String TEST_BIOMETRIC = "android.permission.TEST_BIOMETRIC";
+    field public static final String TEST_INPUT_METHOD = "android.permission.TEST_INPUT_METHOD";
     field public static final String TEST_MANAGE_ROLLBACKS = "android.permission.TEST_MANAGE_ROLLBACKS";
     field public static final String UPGRADE_RUNTIME_PERMISSIONS = "android.permission.UPGRADE_RUNTIME_PERMISSIONS";
     field public static final String WRITE_DEVICE_CONFIG = "android.permission.WRITE_DEVICE_CONFIG";
@@ -3160,8 +3161,8 @@ package android.view.inputmethod {
     method public int getDisplayId();
     method @NonNull @RequiresPermission(android.Manifest.permission.INTERACT_ACROSS_USERS_FULL) public java.util.List<android.view.inputmethod.InputMethodInfo> getInputMethodListAsUser(int);
     method public boolean hasActiveInputConnection(@Nullable android.view.View);
-    method public boolean isInputMethodPickerShown();
-    method @RequiresPermission("android.permission.TEST_INPUT_METHOD") public void setStylusWindowIdleTimeoutForTest(long);
+    method @RequiresPermission(android.Manifest.permission.TEST_INPUT_METHOD) public boolean isInputMethodPickerShown();
+    method @RequiresPermission(android.Manifest.permission.TEST_INPUT_METHOD) public void setStylusWindowIdleTimeoutForTest(long);
     field public static final long CLEAR_SHOW_FORCED_FLAG_WHEN_LEAVING = 214016041L; // 0xcc1a029L
   }
 

core/java/android/view/inputmethod/IInputMethodManagerGlobalInvoker.java

@@ -16,6 +16,7 @@
 
 package android.view.inputmethod;
 
+import android.Manifest;
 import android.annotation.AnyThread;
 import android.annotation.DurationMillisLong;
 import android.annotation.NonNull;
@@ -353,6 +354,7 @@ final class IInputMethodManagerGlobalInvoker {
     }
 
     @AnyThread
+    @RequiresPermission(Manifest.permission.TEST_INPUT_METHOD)
     static boolean isInputMethodPickerShownForTest() {
         final IInputMethodManager service = getService();
         if (service == null) {

core/java/android/view/inputmethod/InputMethodManager.java

@@ -3459,6 +3459,7 @@ public final class InputMethodManager {
      * @hide
      */
     @TestApi
+    @RequiresPermission(Manifest.permission.TEST_INPUT_METHOD)
     public boolean isInputMethodPickerShown() {
         return IInputMethodManagerGlobalInvoker.isInputMethodPickerShownForTest();
     }

core/res/AndroidManifest.xml

@@ -4127,7 +4127,8 @@
         android:protectionLevel="signature" />
 
     <!-- Allows access to Test APIs defined in {@link android.view.inputmethod.InputMethodManager}.
-         @hide -->
+         @hide
+         @TestApi -->
     <permission android:name="android.permission.TEST_INPUT_METHOD"
         android:protectionLevel="signature" />