Revert of Fall back to default media device from preferences if no default is supplied from the command line.

content/browser/media/media_devices_util.cc

Index: content/browser/media/media_devices_util.cc
diff --git a/content/browser/media/media_devices_util.cc b/content/browser/media/media_devices_util.cc
index 722798c5644f8586bc4bfc71753754ebcccbde97..f8320a46fd34be15d1fd8ece6a373c18136972e7 100644
--- a/content/browser/media/media_devices_util.cc
+++ b/content/browser/media/media_devices_util.cc
@@ -49,8 +49,7 @@
   return delegate->GetDefaultMediaDeviceID(media_stream_type);
 }
 
-// This function is intended for testing purposes. It returns an empty string
-// if no default device is supplied via the command line.
+// This function is intended for testing purposes.
 std::string GetDefaultMediaDeviceIDFromCommandLine(
     MediaDeviceType device_type) {
   DCHECK(base::CommandLine::ForCurrentProcess()->HasSwitch(
@@ -95,12 +94,8 @@
     const base::Callback<void(const std::string&)>& callback) {
   if (base::CommandLine::ForCurrentProcess()->HasSwitch(
           switches::kUseFakeDeviceForMediaStream)) {
-    std::string command_line_default_device_id =
-        GetDefaultMediaDeviceIDFromCommandLine(device_type);
-    if (!command_line_default_device_id.empty()) {
-      callback.Run(command_line_default_device_id);
-      return;
-    }
+    callback.Run(GetDefaultMediaDeviceIDFromCommandLine(device_type));
+    return;
   }
 
   BrowserThread::PostTaskAndReplyWithResult(