Added translation policy API.

ios/web_view/public/cwv_translation_controller.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_CONTROLLER_H
 #define IOS_WEB_VIEW_PUBLIC_CWV_TRANSLATION_CONTROLLER_H
 
 #import <ChromeWebView/cwv_export.h>
 #import <Foundation/Foundation.h>
 
 NS_ASSUME_NONNULL_BEGIN
 
 @class CWVTranslationLanguage;
+@class CWVTranslationPolicy;
 @protocol CWVTranslationControllerDelegate;
 
 // The error domain for translation errors.
 extern NSErrorDomain const CWVTranslationErrorDomain;
 
 // Possible error codes during translation.
 // No connectivity.
 extern const NSInteger CWVTranslationErrorNetwork;
 // The translation script failed to initialize.
 extern const NSInteger CWVTranslationErrorInitializationError;
@@ skipping 33 matching lines @@
                        toLanguage:(CWVTranslationLanguage*)targetLanguage;
 
 // Reverts any translations done back to the original page language.
 // Note that the original page language  may be different from |sourceLanguage|
 // passed to |translatePageFromLanguage:toLanguage:| above.
 // This must not be called before the |delegate| receives
 // |translationController:didFinishLanguageDetectionWithResult:error:|.
 // TODO(crbug.com/706289): Document what happens if you call this out of order.
 - (void)revertTranslation;
 
+// Sets or retrieves translation policies associated with a specified language.
+// |pageLanguage| should be the language code of the language.

[Eugene But (OOO till 7-30), 2017/05/12 14:39:20]

Do you want to use nullable annotations? Please document the behavior for empty
host and null page language (if allowed).

[jzw1, 2017/05/15 02:43:31]

The entire thing is wrapped in assume nonnull, which works for us. I added that
pageHost below cannot be empty, also added a DCHECK for it.

+- (void)setTranslationPolicy:(CWVTranslationPolicy*)policy
+             forPageLanguage:(CWVTranslationLanguage*)pageLanguage;
+- (CWVTranslationPolicy*)translationPolicyForPageLanguage:
+    (CWVTranslationLanguage*)pageLanguage;
+
+// Sets or retrieves translation policies associated with a specified page.
+// |pageHost| should be the hostname of the website.
+- (void)setTranslationPolicy:(CWVTranslationPolicy*)policy
+                 forPageHost:(NSString*)pageHost;
+- (CWVTranslationPolicy*)translationPolicyForPageHost:(NSString*)pageHost;
+
 @end
 
 NS_ASSUME_NONNULL_END
 
 #endif  // IOS_WEB_VIEW_PUBLIC_CWV_TRANSLATION_CONTROLLER_H