Make IMM#getCurrentInputMethod{Info,Subtype} consistent

Since it was originall introduced [1],

  InputMethodManager#getCurrentInputMethodInfo()

has been built by using

  Settings.Secure.DEFAULT_INPUT_METHOD

as the source of truth when determinig the currently selected IME for
the given user.

On the other hand,

  InputMethodManager#getCurrentInputMethodSubtype()

uses

  InputMethodBindingController#getCurrentInputMethodSubtype()

as the source of truth when determing the currently selected subtype
for the given user.

With this CL #getCurrentInputMethodInfo() starts using
InputMethodBindingController as the source of truth as well, because
that's what InputMethodManagerService actually does when establishing
a connection.

The new behavior is guarged with a build time flag.

 [1]: I60a0f67bf7d261d3a4a733adcb8a022ceac6e1db
      2422bcffe2351789dc80be68b6f6d5515dc0fa11

Bug: 355034523
Test: presubmit
Flag: build.consistent_get_current_input_method_info
Change-Id: I83716695094a58ee6ceab1a26c6d514c49cb4c15
diff --git a/core/java/android/view/inputmethod/flags.aconfig b/core/java/android/view/inputmethod/flags.aconfig
index e294ee2..cfaaf2b 100644
--- a/core/java/android/view/inputmethod/flags.aconfig
+++ b/core/java/android/view/inputmethod/flags.aconfig
@@ -73,6 +73,17 @@
 }
 
 flag {
+    name: "consistent_get_current_input_method_info"
+    namespace: "input_method"
+    description: "Use BindingController as the source of truth in getCurrentInputMethodInfo"
+    bug: "355034523"
+    is_fixed_read_only: true
+    metadata {
+      purpose: PURPOSE_BUGFIX
+    }
+}
+
+flag {
     name: "ime_switcher_revamp"
     is_exported: true
     namespace: "input_method"
diff --git a/services/core/java/com/android/server/inputmethod/InputMethodManagerService.java b/services/core/java/com/android/server/inputmethod/InputMethodManagerService.java
index eed34b8..c2b7219 100644
--- a/services/core/java/com/android/server/inputmethod/InputMethodManagerService.java
+++ b/services/core/java/com/android/server/inputmethod/InputMethodManagerService.java
@@ -1470,7 +1470,16 @@
                     Manifest.permission.INTERACT_ACROSS_USERS_FULL, null);
         }
         final InputMethodSettings settings = InputMethodSettingsRepository.get(userId);
-        return settings.getMethodMap().get(settings.getSelectedInputMethod());
+        final String selectedImeId;
+        if (Flags.consistentGetCurrentInputMethodInfo()) {
+            final var bindingController = getInputMethodBindingController(userId);
+            synchronized (ImfLock.class) {
+                selectedImeId = bindingController.getSelectedMethodId();
+            }
+        } else {
+            selectedImeId = settings.getSelectedInputMethod();
+        }
+        return settings.getMethodMap().get(selectedImeId);
     }
 
     @BinderThread