Always enable FCM on Windows.

chrome/browser/gpu/chrome_gpu_util.cc

Index: chrome/browser/gpu/chrome_gpu_util.cc
diff --git a/chrome/browser/gpu/chrome_gpu_util.cc b/chrome/browser/gpu/chrome_gpu_util.cc
index 61da773e24cc355eb7b17f70808cc23d7d589970..4bbd5e52c518baa0462db9ade431af9b03c7dcf2 100644
--- a/chrome/browser/gpu/chrome_gpu_util.cc
+++ b/chrome/browser/gpu/chrome_gpu_util.cc
@@ -40,18 +40,6 @@ bool ShouldRunCompositingFieldTrial() {
   return false;
 #endif
 
-// Necessary for linux_chromeos build since it defines both OS_LINUX
-// and OS_CHROMEOS.
-#if defined(OS_CHROMEOS)
-  return false;
-#endif
-
-#if defined(OS_WIN)
-  // Don't run the trial on Windows XP.
-  if (base::win::GetVersion() < base::win::VERSION_VISTA)
-    return false;
-#endif
-
 #if defined(OS_MACOSX)
   // Browser and content shell tests hang on 10.7 when the Apple software
   // renderer is used. These tests ignore the blacklist (which disables