[ash-md] Erases the pre-MD code path for Overview Mode

ash/common/material_design/material_design_controller.cc

Index: ash/common/material_design/material_design_controller.cc
diff --git a/ash/common/material_design/material_design_controller.cc b/ash/common/material_design/material_design_controller.cc
index 74b9e2423504abdf8e7889592a2d3d39180c5bd2..a2c8607d599910686f91c1a9c7f621141ceed04c 100644
--- a/ash/common/material_design/material_design_controller.cc
+++ b/ash/common/material_design/material_design_controller.cc
@@ -58,11 +58,6 @@ MaterialDesignController::Mode MaterialDesignController::GetMode() {
 }
 
 // static
-bool MaterialDesignController::IsOverviewMaterial() {
-  return MaterialDesignController::IsMaterial();
-}
-
-// static
 bool MaterialDesignController::IsShelfMaterial() {
   return MaterialDesignController::IsMaterialExperimental();
 }