Don't use dashed focus painter on back button in MD mode.

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

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #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"
 #include "ui/views/painter.h"
 
 BackButton::BackButton(Profile* profile,
                        views::ButtonListener* listener,
                        ui::MenuModel* model)
     : ToolbarButton(profile, listener, model), margin_leading_(0) {}
 
 BackButton::~BackButton() {}
 
 void BackButton::SetLeadingMargin(int margin) {
   margin_leading_ = margin;
 
   UpdateThemedBorder();
 
-  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));
+  if (!ui::MaterialDesignController::IsModeMaterial()) {

[Peter Kasting, 2016/06/14 22:11:57]

Heh, I'd been thinking to have both conditions here, but since the other
condition should always be true pre-MD, your way is better.

+    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();
 }
 
 const char* BackButton::GetClassName() const {
   return "BackButton";
 }
 
 std::unique_ptr<views::LabelButtonBorder> BackButton::CreateDefaultBorder()
     const {
   std::unique_ptr<views::LabelButtonBorder> border =
       ToolbarButton::CreateDefaultBorder();
 
   // Adjust border insets to follow the margin change,
   // which will be reflected in where the border is painted
   // through GetThemePaintRect().
   const gfx::Insets insets(border->GetInsets());
   border->set_insets(gfx::Insets(insets.top(), insets.left() + margin_leading_,
                                  insets.bottom(), insets.right()));
 
   return border;
 }
 
 gfx::Rect BackButton::GetThemePaintRect() const {
   gfx::Rect rect(LabelButton::GetThemePaintRect());
   const bool is_rtl = base::i18n::IsRTL();
   rect.Inset(is_rtl ? 0 : margin_leading_, 0, is_rtl ? margin_leading_ : 0, 0);
   return rect;
 }