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

ios/chrome/browser/voice/text_to_speech_parser_unittest.mm

+// Copyright 2015 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 <Foundation/Foundation.h>
+
+#import "ios/chrome/browser/voice/text_to_speech_parser.h"
+#include "testing/gtest/include/gtest/gtest.h"
+#import "third_party/google_toolbox_for_mac/src/Foundation/GTMStringEncoding.h"
+
+// Expose internal parser function for testing.
+NSData* ExtractVoiceSearchAudioDataFromPageHTML(NSString* pageHTML);
+
+namespace {
+NSString* const kValidVoiceSearchHTML =
+    @"<script>(function(){var _a_tts='dGVzdGF1ZG8zMm9pbw==';var _m_tts= {}}";
+NSString* const kInvalidVoiceSearchHTML = @"no TTS data";
+}  // namespace
+
+TEST(TextToSpeechParser, ExtractAudioDataValid) {
+  NSData* result =
+      ExtractVoiceSearchAudioDataFromPageHTML(kValidVoiceSearchHTML);
+
+  EXPECT_TRUE(result != nil);
+
+  GTMStringEncoding* base64 = [GTMStringEncoding rfc4648Base64StringEncoding];
+  NSData* expectedData = [base64 decode:@"dGVzdGF1ZG8zMm9pbw=="];
+  EXPECT_TRUE([expectedData isEqualToData:result]);
+}
+
+TEST(TextToSpeechParser, ExtractAudioDataNotFound) {
+  NSData* result =
+      ExtractVoiceSearchAudioDataFromPageHTML(kInvalidVoiceSearchHTML);
+  EXPECT_TRUE(result == nil);
+}