Removing useless Win7 checks + standardize its use

chrome/browser/ui/views/frame/browser_desktop_window_tree_host_win.cc

 // Copyright (c) 2012 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/frame/browser_desktop_window_tree_host_win.h"
 
 #include <dwmapi.h>
 
 #include "base/macros.h"
 #include "base/process/process_handle.h"
@@ skipping 307 matching lines @@
   tabstrip_bounds =
       display::win::ScreenWin::DIPToClientRect(hwnd, tabstrip_bounds);
 
   // Extend inwards far enough to go under the semitransparent client edges.
   const gfx::Insets thicknesses = GetClientEdgeThicknesses();
   gfx::Point left_top = display::win::ScreenWin::DIPToClientPoint(
       hwnd, gfx::Point(thicknesses.left(), thicknesses.top()));
   gfx::Point right_bottom = display::win::ScreenWin::DIPToClientPoint(
       hwnd, gfx::Point(thicknesses.right(), thicknesses.bottom()));
 
-  if (base::win::GetVersion() <= base::win::VERSION_WIN7) {
+  if (base::win::GetVersion() < base::win::VERSION_WIN8) {
     // The 2 px (not DIP) at the inner edges of the glass are a light and
     // dark line, so we must inset further to account for those.
     constexpr gfx::Vector2d kDWMEdgeThickness(2, 2);
     left_top += kDWMEdgeThickness;
     right_bottom += kDWMEdgeThickness;
   }
 
   return MARGINS{left_top.x(), right_bottom.x(),
                  tabstrip_bounds.bottom() + left_top.y(), right_bottom.y()};
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // BrowserDesktopWindowTreeHost, public:
 
 // static
 BrowserDesktopWindowTreeHost*
     BrowserDesktopWindowTreeHost::CreateBrowserDesktopWindowTreeHost(
         views::internal::NativeWidgetDelegate* native_widget_delegate,
         views::DesktopNativeWidgetAura* desktop_native_widget_aura,
         BrowserView* browser_view,
         BrowserFrame* browser_frame) {
   return new BrowserDesktopWindowTreeHostWin(native_widget_delegate,
                                              desktop_native_widget_aura,
                                              browser_view,
                                              browser_frame);
 }