Added translation policy API.

ios/web_view/internal/translate/cwv_translation_policy.mm

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#import "ios/web_view/public/cwv_translation_policy.h"
+
+#import "ios/web_view/public/cwv_translation_language.h"
+
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
+@interface CWVTranslationPolicy ()
+// Internal initializer.
+- (instancetype)initWithType:(CWVTranslationPolicyType)type
+                    language:(CWVTranslationLanguage*)language
+    NS_DESIGNATED_INITIALIZER;
+@end
+
+@implementation CWVTranslationPolicy
+
+@synthesize language = _language;
+@synthesize type = _type;
+
+- (instancetype)initWithType:(CWVTranslationPolicyType)type
+                    language:(CWVTranslationLanguage*)language {
+  self = [super init];
+  if (self) {
+    _type = type;
+    _language = language;
+  }
+  return self;
+}
+
++ (CWVTranslationPolicy*)translationPolicyAsk {
+  return [[CWVTranslationPolicy alloc] initWithType:CWVTranslationPolicyAsk
+                                           language:nil];
+}
+
++ (CWVTranslationPolicy*)translationPolicyNever {
+  return [[CWVTranslationPolicy alloc] initWithType:CWVTranslationPolicyNever
+                                           language:nil];
+}
+
++ (CWVTranslationPolicy*)translationPolicyAutoTranslateToLanguage:
+    (CWVTranslationLanguage*)language {
+  return [[CWVTranslationPolicy alloc] initWithType:CWVTranslationPolicyAuto
+                                           language:language];
+}
+
+@end