Implemented new Translate API for purely Objective-C clients.

ios/web_view/public/cwv_translation_controller_delegate.h

Index: ios/web_view/public/cwv_translation_controller_delegate.h
diff --git a/ios/web_view/public/cwv_translation_controller_delegate.h b/ios/web_view/public/cwv_translation_controller_delegate.h
new file mode 100644
index 0000000000000000000000000000000000000000..ef09de64629d5bbe60fb60ef91a5a414cf30f257
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+++ b/ios/web_view/public/cwv_translation_controller_delegate.h
@@ -0,0 +1,46 @@
+// 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 <ChromeWebView/cwv_export.h>
+#import <Foundation/Foundation.h>
+
+#ifndef IOS_WEB_VIEW_PUBLIC_CWV_TRANSLATION_CONTROLLER_DELEGATE_H
+#define IOS_WEB_VIEW_PUBLIC_CWV_TRANSLATION_CONTROLLER_DELEGATE_H
+
+NS_ASSUME_NONNULL_BEGIN
+
+@class CWVTranslationController;
+@class CWVLanguageDetectionResult;
+@class CWVTranslationLanguage;
+
+// Updates delegate on translation progress.
+CWV_EXPORT
+@protocol CWVTranslationControllerDelegate<NSObject>
+
+@required
+// Called when language detection is completed. Contains information on the
+// detected language, the assumed target language for translation, as well as
+// all languages supported by this translation controller.
+// |error| will be nonnull if language detection failed.
+- (void)translationController:(CWVTranslationController*)controller
+    didFinishLanguageDetectionWithResult:(CWVLanguageDetectionResult*)result
+                                   error:(nullable NSError*)error;
+
+@optional
+// Called when a translation has started.
+- (void)translationController:(CWVTranslationController*)controller
+    didStartTranslationFromLanguage:(CWVTranslationLanguage*)sourceLanguage
+                         toLanguage:(CWVTranslationLanguage*)targetLanguage;
+
+// Called when translation finishes. |error| will be nonnull if it failed.
+- (void)translationController:(CWVTranslationController*)controller
+    didFinishTranslationFromLanguage:(CWVTranslationLanguage*)sourceLanguage
+                          toLanguage:(CWVTranslationLanguage*)targetLanguage
+                               error:(nullable NSError*)error;
+
+@end
+
+NS_ASSUME_NONNULL_END
+
+#endif  // IOS_WEB_VIEW_PUBLIC_CWV_TRANSLATION_CONTROLLER_DELEGATE_H