[ios] Adds a provider API for AudioSessionController.

ios/public/provider/chrome/browser/chrome_browser_provider.h

Index: ios/public/provider/chrome/browser/chrome_browser_provider.h
diff --git a/ios/public/provider/chrome/browser/chrome_browser_provider.h b/ios/public/provider/chrome/browser/chrome_browser_provider.h
index 599c59183844617d0c3f352a9c8f55fe93ab79be..a5b7c6bd150662d79d90eedbb2c3b8b8bd1bad5a 100644
--- a/ios/public/provider/chrome/browser/chrome_browser_provider.h
+++ b/ios/public/provider/chrome/browser/chrome_browser_provider.h
@@ -60,6 +60,7 @@ class GeolocationUpdaterProvider;
 class SigninResourcesProvider;
 class LiveTabContextProvider;
 class UpdatableResourceProvider;
+class VoiceSearchProvider;
 
 // Setter and getter for the provider. The provider should be set early, before
 // any browser code is called.
@@ -141,8 +142,12 @@ class ChromeBrowserProvider {
   virtual bool IsSafeBrowsingEnabled(const base::Closure& on_update_callback);
 
   // Returns the list of available voice search languages.
+  // TODO(rohitrao): Remove once callers are going through VoiceSearchProvider.
   virtual NSArray* GetAvailableVoiceSearchLanguages() const;
 
+  // Returns an instance of the voice search provider, if one exists.
+  virtual VoiceSearchProvider* GetVoiceSearchProvider();

[sdefresne, 2016/10/18 22:19:43]

This method should be const.

[rohitrao (ping after 24h), 2016/10/18 23:30:44]

Done.

+
   // Returns the SyncedWindowDelegatesGetter implementation.
   virtual std::unique_ptr<sync_sessions::SyncedWindowDelegatesGetter>
   CreateSyncedWindowDelegatesGetter(ios::ChromeBrowserState* browser_state);