Make activities have a thick border when in overview mode part 1

athena/activity/public/activity_view_model.h

Index: athena/activity/public/activity_view_model.h
diff --git a/athena/activity/public/activity_view_model.h b/athena/activity/public/activity_view_model.h
index 99241c8a6a338e049d59ecc7d1db1ca136458819..12b8ceda8e17324cca7489e6742273d0988cec22 100644
--- a/athena/activity/public/activity_view_model.h
+++ b/athena/activity/public/activity_view_model.h
@@ -57,6 +57,12 @@ class ATHENA_EXPORT ActivityViewModel {
   // GetRepresentativeColor() should be used to clear the preview area.
   // Note: We intentionally do not use a layer / view for this.
   virtual gfx::ImageSkia GetOverviewModeImage() = 0;
+
+  // Prepares the contents view for overview.
+  virtual void PrepareContentsForOverview() = 0;
+
+  // Undoes any changes done by PrepareContentsForOverview().
+  virtual void ResetContentsView() = 0;
 };
 
 }  // namespace athena