Add interface for DesktopMediaPickerModel

chrome/browser/media/desktop_media_picker_model.cc

Index: chrome/browser/media/desktop_media_picker_model.cc
diff --git a/chrome/browser/media/desktop_media_picker_model.cc b/chrome/browser/media/desktop_media_picker_model.cc
index 741fb1cc511c86a8853fdb8e8482d2a07187ddf6..c64dc1013d2d059ec2704018c7383df533f79669 100644
--- a/chrome/browser/media/desktop_media_picker_model.cc
+++ b/chrome/browser/media/desktop_media_picker_model.cc
@@ -258,6 +258,15 @@ void DesktopMediaPickerModel::StartUpdating(Observer* observer) {
   Refresh();
 }
 
+int DesktopMediaPickerModel::source_count() const {
+  return sources_.size();
+}
+
+const DesktopMediaPickerModel::Source& DesktopMediaPickerModel::source(
+    int index) const {
+  return sources_[index];
+}
+
 // static
 bool DesktopMediaPickerModel::CompareSources(const SourceDescription& a,
                                              const SourceDescription& b) {