Add functionality to get default media device IDs from user preferences.

chrome/browser/ui/browser.cc

Index: chrome/browser/ui/browser.cc
diff --git a/chrome/browser/ui/browser.cc b/chrome/browser/ui/browser.cc
index ffcba101a4ca46844c2099124d03471d307fda4c..f136d01a35148a06a3a2101951b406bbb3688482 100644
--- a/chrome/browser/ui/browser.cc
+++ b/chrome/browser/ui/browser.cc
@@ -61,6 +61,7 @@
 #include "chrome/browser/lifetime/keep_alive_registry.h"
 #include "chrome/browser/lifetime/keep_alive_types.h"
 #include "chrome/browser/lifetime/scoped_keep_alive.h"
+#include "chrome/browser/media/webrtc/media_capture_devices_dispatcher.h"
 #include "chrome/browser/memory/tab_manager_web_contents_data.h"
 #include "chrome/browser/notifications/notification_ui_manager.h"
 #include "chrome/browser/pepper_broker_infobar_delegate.h"
@@ -1829,6 +1830,14 @@ bool Browser::CheckMediaAccessPermission(content::WebContents* web_contents,
   return ::CheckMediaAccessPermission(web_contents, security_origin, type);
 }
 
+std::string Browser::GetDefaultMediaDeviceID(content::WebContents* web_contents,
+                                             content::MediaStreamType type) {
+  Profile* profile =
+      Profile::FromBrowserContext(web_contents->GetBrowserContext());
+  return MediaCaptureDevicesDispatcher::GetInstance()
+      ->GetDefaultDeviceIDForProfile(profile, type);
+}
+
 bool Browser::RequestPpapiBrokerPermission(
     WebContents* web_contents,
     const GURL& url,