[ios] Adds support for parsing Text-to-Speech search results.

ios/chrome/browser/voice/text_to_speech_listener.h

Index: ios/chrome/browser/voice/text_to_speech_listener.h
diff --git a/ios/chrome/browser/voice/text_to_speech_listener.h b/ios/chrome/browser/voice/text_to_speech_listener.h
new file mode 100644
index 0000000000000000000000000000000000000000..8ad3595541f22f46cf92dce441b54ff81de13640
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+++ b/ios/chrome/browser/voice/text_to_speech_listener.h
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+// Copyright 2016 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_CHROME_BROWSER_VOICE_TEXT_TO_SPEECH_LISTENER_H_
+#define IOS_CHROME_BROWSER_VOICE_TEXT_TO_SPEECH_LISTENER_H_
+
+#import <Foundation/Foundation.h>
+
+class GURL;
+namespace web {
+class WebState;
+}
+
+@protocol TextToSpeechListenerDelegate;
+
+// Class that listens for page loads on a WebState and extracts TTS data.
+@interface TextToSpeechListener : NSObject
+
+// The WebState passed on initialization.
+@property(nonatomic, readonly) web::WebState* webState;
+
+// Designated initializer.
+- (instancetype)initWithWebState:(web::WebState*)webState
+                        delegate:(id<TextToSpeechListenerDelegate>)delegate
+    NS_DESIGNATED_INITIALIZER;
+- (instancetype)init NS_UNAVAILABLE;
+
+@end
+
+@protocol TextToSpeechListenerDelegate<NSObject>
+
+// Called by |listener| when TTS audio data has been extracted from its
+// WebState.  If a page load was encountered that was not a Voice Search SRP,
+// this function is called with a nil |result|.
+- (void)textToSpeechListener:(TextToSpeechListener*)listener
+            didReceiveResult:(NSData*)result;
+
+// Called by |listener| after its WebState is destroyed.
+- (void)textToSpeechListenerWebStateWasDestroyed:
+    (TextToSpeechListener*)listener;
+
+// Called by |listener| to determine whether |URL| is a Voice Search SRP with
+// Text-To-Speech data.
+- (BOOL)shouldTextToSpeechListener:(TextToSpeechListener*)listener
+                  parseDataFromURL:(const GURL&)URL;
+
+@end
+
+#endif  // IOS_CHROME_BROWSER_VOICE_TEXT_TO_SPEECH_LISTENER_H_