Unify if guards of GetLinuxWindowManager.

chrome/browser/metrics/chrome_browser_main_extra_parts_metrics.cc

 // Copyright (c) 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/metrics/chrome_browser_main_extra_parts_metrics.h"
 
 #include <string>
 
 #include "base/bind.h"
 #include "base/command_line.h"
@@ skipping 265 matching lines @@
       if (translated_glibc_minor_version >= UMA_LINUX_GLIBC_2_11) {
         glibc_version_result =
             static_cast<UMALinuxGlibcVersion>(translated_glibc_minor_version);
       }
     }
   }
   UMA_HISTOGRAM_SPARSE_SLOWLY("Linux.GlibcVersion", glibc_version_result);
 #endif
 }
 
-#if defined(USE_X11) && !defined(OS_CHROMEOS)
+#if defined(OS_LINUX) && defined(USE_X11) && !defined(OS_CHROMEOS)
 UMALinuxWindowManager GetLinuxWindowManager() {
   switch (ui::GuessWindowManager()) {
     case ui::WM_OTHER:
       return UMA_LINUX_WINDOW_MANAGER_OTHER;
     case ui::WM_UNNAMED:
       return UMA_LINUX_WINDOW_MANAGER_UNNAMED;
     case ui::WM_AWESOME:
       return UMA_LINUX_WINDOW_MANAGER_AWESOME;
     case ui::WM_BLACKBOX:
       return UMA_LINUX_WINDOW_MANAGER_BLACKBOX;
@@ skipping 240 matching lines @@
   }
 }
 
 namespace chrome {
 
 void AddMetricsExtraParts(ChromeBrowserMainParts* main_parts) {
   main_parts->AddParts(new ChromeBrowserMainExtraPartsMetrics());
 }
 
 }  // namespace chrome