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

ios/chrome/browser/voice/text_to_speech_listener.mm

Index: ios/chrome/browser/voice/text_to_speech_listener.mm
diff --git a/ios/chrome/browser/voice/text_to_speech_listener.mm b/ios/chrome/browser/voice/text_to_speech_listener.mm
new file mode 100644
index 0000000000000000000000000000000000000000..aa95344945425791d9791fa87d95576e36b7a595
--- /dev/null
+++ b/ios/chrome/browser/voice/text_to_speech_listener.mm
@@ -0,0 +1,110 @@
+// 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.
+
+#import "ios/chrome/browser/voice/text_to_speech_listener.h"
+
+#include <memory>
+
+#include "base/ios/weak_nsobject.h"
+#include "base/logging.h"
+#include "base/mac/scoped_nsobject.h"
+#include "ios/web/public/navigation_manager.h"
+#include "ios/web/public/web_state/web_state.h"
+#include "ios/web/public/web_state/web_state_observer.h"
+#import "ios/chrome/browser/voice/text_to_speech_parser.h"
+#import "ios/chrome/browser/voice/voice_search_url_rewriter.h"
+#include "url/gurl.h"
+
+#pragma mark - TextToSpeechListener Private Interface
+
+class TextToSpeechWebStateObserver;
+
+@interface TextToSpeechListener () {

[sdefresne, 2016/10/25 13:20:30]

nit: move the ivar declaration to @implementation

[rohitrao (ping after 24h), 2016/10/25 15:23:12]

Done.

+  // Backing object for property of the same name.
+  base::WeakNSProtocol<id<TextToSpeechListenerDelegate>> _delegate;
+  // The TextToSpeechWebStateObserver that listens for Text-To-Speech data.
+  std::unique_ptr<TextToSpeechWebStateObserver> _webStateObserver;

[sdefresne, 2016/10/25 13:20:30]

I think it could be just std::unique_ptr<web::WebStateObserver> as only method
of the sub-class are called, which would allow removing the forward-declaration
of the class and moving it to an anonymous namespace (unless it is friend with
some class).

[rohitrao (ping after 24h), 2016/10/25 15:23:12]

Protected destructor on web::WebStateObserver prevents this.

+}
+
+// The TextToSpeechListenerDelegate passed on initialization.
+@property(nonatomic, readonly) id<TextToSpeechListenerDelegate> delegate;
+
+@end
+
+#pragma mark - TextToSpeechWebStateObserver
+
+class TextToSpeechWebStateObserver : public web::WebStateObserver {
+ public:
+  TextToSpeechWebStateObserver(web::WebState* web_state,
+                               TextToSpeechListener* listener);
+  ~TextToSpeechWebStateObserver() override;
+
+  // web::WebStateObserver implementation:
+  void PageLoaded(
+      web::PageLoadCompletionStatus load_completion_status) override;
+  void WebStateDestroyed() override;
+
+ private:
+  TextToSpeechListener* listener_;
+};
+
+TextToSpeechWebStateObserver::TextToSpeechWebStateObserver(
+    web::WebState* web_state,
+    TextToSpeechListener* listener)
+    : web::WebStateObserver(web_state), listener_(listener) {
+  DCHECK(web_state);
+  DCHECK(listener);
+  // Rewrite the next loaded URL to have the voice search flags.
+  web_state->GetNavigationManager()->AddTransientURLRewriter(
+      &VoiceSearchURLRewriter);
+}
+
+TextToSpeechWebStateObserver::~TextToSpeechWebStateObserver() {}
+
+void TextToSpeechWebStateObserver::PageLoaded(
+    web::PageLoadCompletionStatus load_completion_status) {
+  GURL url = web_state()->GetLastCommittedURL();

[sdefresne, 2016/10/25 13:20:30]

nit: const GURL& url = ...

[rohitrao (ping after 24h), 2016/10/25 15:23:12]

Done.

+  BOOL shouldParse = [listener_.delegate shouldTextToSpeechListener:listener_
+                                                   parseDataFromURL:url];
+  if (shouldParse) {
+    base::WeakNSObject<TextToSpeechListener> weakListener(listener_);
+    ExtractVoiceSearchAudioDataFromWebState(web_state(), ^(NSData* audioData) {
+      [[weakListener delegate] textToSpeechListener:weakListener
+                                  didReceieveResult:audioData];
+    });
+  } else {
+    [listener_.delegate textToSpeechListener:listener_ didReceieveResult:nil];
+  }
+}
+
+void TextToSpeechWebStateObserver::WebStateDestroyed() {
+  [listener_.delegate textToSpeechListenerWebStateWasDestroyed:listener_];
+}
+
+#pragma mark - TextToSpeechListener
+
+@implementation TextToSpeechListener
+
+- (instancetype)initWithWebState:(web::WebState*)webState
+                        delegate:(id<TextToSpeechListenerDelegate>)delegate {
+  if ((self = [super init])) {
+    DCHECK(webState);
+    DCHECK(delegate);
+    _webStateObserver.reset(new TextToSpeechWebStateObserver(webState, self));
+    _delegate.reset(delegate);
+  }
+  return self;
+}
+
+#pragma mark Accessors
+
+- (web::WebState*)webState {
+  return _webStateObserver->web_state();
+}
+
+- (id<TextToSpeechListenerDelegate>)delegate {
+  return _delegate.get();
+}
+
+@end