Added translation policy API.

ios/web_view/public/cwv_translation_policy.h

+// 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.
+
+#ifndef IOS_WEB_VIEW_PUBLIC_CWV_TRANSLATION_POLICY_H
+#define IOS_WEB_VIEW_PUBLIC_CWV_TRANSLATION_POLICY_H
+
+#import <ChromeWebView/cwv_export.h>
+#import <Foundation/Foundation.h>
+
+NS_ASSUME_NONNULL_BEGIN
+
+@class CWVTranslationLanguage;
+
+typedef NS_ENUM(NSInteger, CWVTranslationPolicyType) {
+  CWVTranslationPolicyAsk = 1,  // Prompt user on whether or not to translate.
+  CWVTranslationPolicyNever,    // Never translate.
+  CWVTranslationPolicyAuto      // Automatically translate according to policy.
+};
+
+// Represents a translation policy that can associated with another object like
+// a language or website hostname.
+CWV_EXPORT
+@interface CWVTranslationPolicy : NSObject
+
+- (instancetype)init NS_UNAVAILABLE;
+
+// Creates a policy with CWVTranslationPolicyAsk and null language.
++ (CWVTranslationPolicy*)translationPolicyAsk;
+// Creates a policy with CWVTranslationPolicyNever and null language.
++ (CWVTranslationPolicy*)translationPolicyNever;
+// Creates a policy with CWVTranslationPolicyAuto and the given language.
++ (CWVTranslationPolicy*)translationPolicyAutoTranslateToLanguage:
+    (CWVTranslationLanguage*)language;
+
+// Policy type.
+@property(nonatomic, readonly) CWVTranslationPolicyType type;
+
+// Indicates the target language to automatically translate to.
+// null unless |type| is CWVTranslationPolicyAuto.

[sdefresne, 2017/05/17 09:47:30]

null -> Nil (since it is a Objective-C type).

If you want to avoid capitalizing the N, then you can reformulate this to

// Indicates the target language to automatically translate to. Only defined
// if |type| is CWVTranslationPolicyAuto.

[Hiroshi Ichikawa, 2017/05/18 02:34:56]

eugenebut@ said he perfers nil to Nil because Nil means a dfferent thing in
Objective-C.
I personally agree with him to prefer Objective-C correctness to English
correctness here, but if you do care, your proposed refinement sounds good. Or
maybe just add "It is":

// It is nil unless |type| is CWVTranslationPolicyAuto.

[jzw1, 2017/05/19 02:40:58]

I'll do "It is nil"

+@property(nonatomic, readonly) CWVTranslationLanguage* language;
+
+@end
+
+NS_ASSUME_NONNULL_END
+
+#endif  // IOS_WEB_VIEW_PUBLIC_CWV_TRANSLATION_POLICY_H