Added translation policy API.

ios/web_view/public/cwv_translation_policy.h

Index: ios/web_view/public/cwv_translation_policy.h
diff --git a/ios/web_view/public/cwv_translation_policy.h b/ios/web_view/public/cwv_translation_policy.h
new file mode 100644
index 0000000000000000000000000000000000000000..79c8cd473a2b9037f5d630fd9d258b31e1e3f16d
--- /dev/null
+++ b/ios/web_view/public/cwv_translation_policy.h
@@ -0,0 +1,43 @@
+// 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,    // Prompt user on whether or not to translate.

[Eugene But (OOO till 7-30), 2017/05/11 15:48:59]

nit: It's a good practice to initialize first enum item (in this case with 1,
because 0 is default in Objective-C).

[jzw1, 2017/05/12 03:46:46]

Done.

+  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
+
+// Convenience constructors.

[Eugene But (OOO till 7-30), 2017/05/11 15:48:59]

Technically Objective-C does not have constructors. In the comments, please
explain each convenience method (which type and language the resulting policy
will have).

[jzw1, 2017/05/12 03:46:47]

Done.

++ (CWVTranslationPolicy*)translationPolicyAsk;
++ (CWVTranslationPolicy*)translationPolicyNever;
++ (CWVTranslationPolicy*)translationPolicyAutoTranslateToLanguage:
+    (CWVTranslationLanguage*)language;
+
+// Policy type.
+@property(nonatomic, readonly) CWVTranslationPolicyType type;
+

[Eugene But (OOO till 7-30), 2017/05/11 15:48:59]

- (instancetype)init NS_UNAVAILABLE;

[jzw1, 2017/05/12 03:46:47]

Is there a way to have this and still allow the implementation file to call
init?

[michaeldo, 2017/05/12 15:29:08]

It should be defined here as unavailable. Usually we have an initializer that
takes a param defined elsewhere in an _internal header (if other classes need to
internally allocate it) or in the implementation file if no classes need it. You
can define |initWithType| inside |cwv_translation_policy.mm|

[jzw1, 2017/05/15 02:43:27]

Sounds good. Thanks.

+// Indicates the target language to automatically translate to.
+// Nil unless |type| is CWVTranslationPolicyAuto.

[Eugene But (OOO till 7-30), 2017/05/11 15:48:59]

nit: s/Nil/nil

Uppercase Nil is a real thing which is used for classes.

[jzw1, 2017/05/12 03:46:47]

Done.

[Eugene But (OOO till 7-30), 2017/05/12 14:39:19]

FYI: There is still uppercase Nil

[jzw1, 2017/05/15 02:43:27]

Done.

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