MacViews: Fix mac_views_browser compilation due to unused variable on Mac.

chrome/browser/ui/views/profiles/avatar_button.cc

 // Copyright 2014 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/profiles/avatar_button.h"
 
 #include <utility>
 
 #include "chrome/app/vector_icons/vector_icons.h"
 #include "chrome/browser/browser_process.h"
@@ skipping 182 matching lines @@
 
   bool apply_ink_drop = IsCondensible();
 #if defined(OS_LINUX)
   DCHECK_EQ(AvatarButtonStyle::THEMED, button_style);
   apply_ink_drop = true;
 #endif
 
   if (apply_ink_drop) {
     SetInkDropMode(InkDropMode::ON);
     SetFocusPainter(nullptr);
+#if defined(OS_LINUX)
     constexpr int kIconSize = 16;
-#if defined(OS_LINUX)
     set_ink_drop_base_color(SK_ColorWHITE);
     SetBorder(base::MakeUnique<AvatarButtonThemedBorder>());
     generic_avatar_ = gfx::CreateVectorIcon(kProfileSwitcherOutlineIcon,
                                             kIconSize, gfx::kPlaceholderColor);
 #elif defined(OS_WIN)
+    constexpr int kIconSize = 16;
     DCHECK_EQ(AvatarButtonStyle::NATIVE, button_style);
     set_ink_drop_base_color(SK_ColorBLACK);
     SetBorder(views::CreateEmptyBorder(kBorderInsets));
     constexpr SkColor kIconColor =
         SkColorSetA(SK_ColorBLACK, static_cast<SkAlpha>(0.54 * 0xFF));
     generic_avatar_ =
         gfx::CreateVectorIcon(kAccountCircleIcon, kIconSize, kIconColor);
 #endif  // defined(OS_WIN)
   } else if (button_style == AvatarButtonStyle::THEMED) {
     const int kNormalImageSet[] = IMAGE_GRID(IDR_AVATAR_THEMED_BUTTON_NORMAL);
@@ skipping 210 matching lines @@
 
 // TODO(estade): all versions of this button should condense.
 bool AvatarButton::IsCondensible() const {
 #if defined(OS_WIN)
   return (base::win::GetVersion() >= base::win::VERSION_WIN10) &&
          button_style_ == AvatarButtonStyle::NATIVE;
 #else
   return false;
 #endif
 }