Implement CancelUserMediaRequest for the browser part

content/browser/renderer_host/media/media_stream_device_settings.cc

Index: content/browser/renderer_host/media/media_stream_device_settings.cc
diff --git a/content/browser/renderer_host/media/media_stream_device_settings.cc b/content/browser/renderer_host/media/media_stream_device_settings.cc
index 78b895d15007798b9ef502f2075eee82e3b91641..39d66e7a5b2693abfd124a9638a65eb6eed3e67f 100644
--- a/content/browser/renderer_host/media/media_stream_device_settings.cc
+++ b/content/browser/renderer_host/media/media_stream_device_settings.cc
@@ -134,6 +134,18 @@ void MediaStreamDeviceSettings::RequestCaptureDeviceUsage(
       render_process_id, render_view_id, security_origin, request_options)));
 }
 
+void MediaStreamDeviceSettings::RemovePendingCaptureRequest(
+    const std::string& label) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+
+  SettingsRequests::iterator request_it = requests_.find(label);
+  if (request_it != requests_.end()) {
+    MediaStreamDeviceSettingsRequest* request = request_it->second;
+    requests_.erase(request_it);
+    delete request;
+  }
+}
+
 void MediaStreamDeviceSettings::AvailableDevices(
     const std::string& label,
     MediaStreamType stream_type,