Remove a bunch of pre-MD toolbar code and assets.

chrome/browser/ui/views/toolbar/back_button.cc

Index: chrome/browser/ui/views/toolbar/back_button.cc
diff --git a/chrome/browser/ui/views/toolbar/back_button.cc b/chrome/browser/ui/views/toolbar/back_button.cc
index b39510683f84315158db586f1d5fcb01093f73b2..444e76e15b4210b8fd6b95a2a20ba044cf943d00 100644
--- a/chrome/browser/ui/views/toolbar/back_button.cc
+++ b/chrome/browser/ui/views/toolbar/back_button.cc
@@ -4,7 +4,6 @@
 
 #include "chrome/browser/ui/views/toolbar/back_button.h"
 
-#include "ui/base/material_design/material_design_controller.h"
 #include "ui/gfx/geometry/insets.h"
 #include "ui/views/animation/ink_drop.h"
 #include "ui/views/controls/button/label_button_border.h"
@@ -19,16 +18,7 @@ BackButton::~BackButton() {}
 
 void BackButton::SetLeadingMargin(int margin) {
   margin_leading_ = margin;
-
   UpdateThemedBorder();
-
-  if (!ui::MaterialDesignController::IsModeMaterial()) {
-    const int inset = LabelButton::kFocusRectInset;
-    const bool is_rtl = base::i18n::IsRTL();
-    const gfx::Insets insets(inset, inset + (is_rtl ? 0 : margin),
-                             inset, inset + (is_rtl ? margin : 0));
-    SetFocusPainter(views::Painter::CreateDashedFocusPainterWithInsets(insets));
-  }
   InvalidateLayout();
 }