Implement IMM#showInputMethodAndSubtypeEnabler() in the client side

With this CL,

  InputMethodManager#showInputMethodAndSubtypeEnabler()

is fully implemented in the client side.  By not using system_server
privileged context to launch the Settings activity, we can stop
worrying about conflicts with existing security concepts such as

 * Background Activity launch blocking mechanism
 * Restrictions for instant apps

Bug: 34886274
Test: Manually verified as follows.
 1. Build aosp_coral-userdebug and flash it.
 2. adb install -r $ANDROID_TARGET_OUT_TESTCASES/ApiDemos/arm64/ApiDemos.apk
 3. adb shell am start -n com.example.android.apis/.ApiDemos
 4. View -> Input Method -> ShowInputMethodAndSubtypeEnabler
 5. Verify that the API works.
Change-Id: I5199ca4609c03900a0e86011d344b054b1df08dd

core/java/android/view/inputmethod/IInputMethodManagerInvoker.java

@@ -179,16 +179,6 @@ final class IInputMethodManagerInvoker {
         }
     }
 
-    @AnyThread
-    void showInputMethodAndSubtypeEnablerFromClient(@NonNull IInputMethodClient client,
-            @Nullable String imeId) {
-        try {
-            mTarget.showInputMethodAndSubtypeEnablerFromClient(client, imeId);
-        } catch (RemoteException e) {
-            throw e.rethrowFromSystemServer();
-        }
-    }
-
     @AnyThread
     boolean isInputMethodPickerShownForTest() {
         try {

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

@@ -53,9 +53,11 @@ import android.compat.annotation.UnsupportedAppUsage;
 import android.content.ComponentName;
 import android.content.ContentResolver;
 import android.content.Context;
+import android.content.Intent;
 import android.content.pm.PackageManager;
 import android.graphics.Matrix;
 import android.graphics.Rect;
+import android.hardware.display.DisplayManager;
 import android.inputmethodservice.InputMethodService;
 import android.os.Binder;
 import android.os.Build;
@@ -71,6 +73,7 @@ import android.os.ServiceManager.ServiceNotFoundException;
 import android.os.Trace;
 import android.os.UserHandle;
 import android.provider.Settings;
+import android.text.TextUtils;
 import android.text.style.SuggestionSpan;
 import android.util.Log;
 import android.util.Pools.Pool;
@@ -3243,7 +3246,26 @@ public final class InputMethodManager {
      * subtypes of all input methods will be shown.
      */
     public void showInputMethodAndSubtypeEnabler(@Nullable String imiId) {
-        mServiceInvoker.showInputMethodAndSubtypeEnablerFromClient(mClient, imiId);
+        Context context = null;
+        synchronized (mH) {
+            if (mCurRootView != null) {
+                context = mCurRootView.mContext;
+            }
+        }
+        if (context == null) {
+            final Context appContext = ActivityThread.currentApplication();
+            final DisplayManager displayManager = appContext.getSystemService(DisplayManager.class);
+            context = appContext.createDisplayContext(displayManager.getDisplay(mDisplayId));
+        }
+
+        final Intent intent = new Intent(Settings.ACTION_INPUT_METHOD_SUBTYPE_SETTINGS);
+        intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK
+                | Intent.FLAG_ACTIVITY_RESET_TASK_IF_NEEDED
+                | Intent.FLAG_ACTIVITY_CLEAR_TOP);
+        if (!TextUtils.isEmpty(imiId)) {
+            intent.putExtra(Settings.EXTRA_INPUT_METHOD_ID, imiId);
+        }
+        context.startActivity(intent);
     }
 
     /**

core/java/com/android/internal/view/IInputMethodManager.aidl

@@ -82,9 +82,6 @@ interface IInputMethodManager {
     void showInputMethodPickerFromSystem(in IInputMethodClient client,
             int auxiliarySubtypeMode, int displayId);
 
-    void showInputMethodAndSubtypeEnablerFromClient(in IInputMethodClient client,
-            @nullable String topId);
-
     @JavaPassthrough(annotation="@android.annotation.RequiresPermission(value = "
             + "android.Manifest.permission.TEST_INPUT_METHOD)")
     boolean isInputMethodPickerShownForTest();

services/core/java/com/android/server/inputmethod/InputMethodManagerService.java

@@ -4051,18 +4051,6 @@ public final class InputMethodManagerService extends IInputMethodManager.Stub
         }
     }
 
-    @Override
-    public void showInputMethodAndSubtypeEnablerFromClient(
-            IInputMethodClient client, String inputMethodId) {
-        synchronized (ImfLock.class) {
-            // TODO(yukawa): Should we verify the display ID?
-            if (!calledFromValidUserLocked()) {
-                return;
-            }
-            showInputMethodAndSubtypeEnabler(inputMethodId);
-        }
-    }
-
     @BinderThread
     private boolean switchToPreviousInputMethod(@NonNull IBinder token) {
         synchronized (ImfLock.class) {
@@ -5219,23 +5207,6 @@ public final class InputMethodManagerService extends IInputMethodManager.Stub
 
     // ----------------------------------------------------------------------
 
-    private void showInputMethodAndSubtypeEnabler(String inputMethodId) {
-        Intent intent = new Intent(Settings.ACTION_INPUT_METHOD_SUBTYPE_SETTINGS);
-        intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK
-                | Intent.FLAG_ACTIVITY_RESET_TASK_IF_NEEDED
-                | Intent.FLAG_ACTIVITY_CLEAR_TOP);
-        if (!TextUtils.isEmpty(inputMethodId)) {
-            intent.putExtra(Settings.EXTRA_INPUT_METHOD_ID, inputMethodId);
-        }
-        final int userId;
-        synchronized (ImfLock.class) {
-            userId = mSettings.getCurrentUserId();
-        }
-        mContext.startActivityAsUser(intent, null, UserHandle.of(userId));
-    }
-
-    // ----------------------------------------------------------------------
-
     /**
      * Enable or disable the given IME by updating {@link Settings.Secure#ENABLED_INPUT_METHODS}.
      *