Support EditorInfo#hintLocales in compat library.

This CL updates LatinIME's compatibility library so that we can access
EditorInfo#hintLocales without directly depending on unreleased SDK.

Bug: 22859862
Change-Id: I4ba7d294bc314002c3abf8842f097a4249783364

java/src/com/android/inputmethod/compat/EditorInfoCompatUtils.java

@@ -19,6 +19,7 @@ package com.android.inputmethod.compat;
 import android.view.inputmethod.EditorInfo;
 
 import java.lang.reflect.Field;
+import java.util.Locale;
 
 public final class EditorInfoCompatUtils {
     // Note that EditorInfo.IME_FLAG_FORCE_ASCII has been introduced
@@ -27,6 +28,8 @@ public final class EditorInfoCompatUtils {
             EditorInfo.class, "IME_FLAG_FORCE_ASCII");
     private static final Integer OBJ_IME_FLAG_FORCE_ASCII = (Integer) CompatUtils.getFieldValue(
             null /* receiver */, null /* defaultValue */, FIELD_IME_FLAG_FORCE_ASCII);
+    private static final Field FIELD_HINT_LOCALES = CompatUtils.getField(
+            EditorInfo.class, "hintLocales");
 
     private EditorInfoCompatUtils() {
         // This utility class is not publicly instantiable.
@@ -78,4 +81,15 @@ public final class EditorInfoCompatUtils {
         }
         return (action != null) ? flags + action : flags.toString();
     }
+
+    public static Locale getPrimaryHintLocale(final EditorInfo editorInfo) {
+        if (editorInfo == null) {
+            return null;
+        }
+        final Object localeList = CompatUtils.getFieldValue(editorInfo, null, FIELD_HINT_LOCALES);
+        if (localeList == null) {
+            return null;
+        }
+        return LocaleListCompatUtils.getPrimary(localeList);
+    }
 }

java/src/com/android/inputmethod/compat/LocaleListCompatUtils.java

@@ -0,0 +1,34 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.inputmethod.compat;
+
+import java.lang.reflect.Method;
+import java.util.Locale;
+
+public final class LocaleListCompatUtils {
+    private static final Class CLASS_LocaleList = CompatUtils.getClass("android.util.LocaleList");
+    private static final Method METHOD_getPrimary =
+            CompatUtils.getMethod(CLASS_LocaleList, "getPrimary");
+
+    private LocaleListCompatUtils() {
+        // This utility class is not publicly instantiable.
+    }
+
+    public static Locale getPrimary(final Object localeList) {
+        return (Locale) CompatUtils.invoke(localeList, null, METHOD_getPrimary);
+    }
+}