Remove Windows snapshot code.

ui/snapshot/BUILD.gn

 # 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.
 
 import("//build/config/ui.gni")
 
 component("snapshot") {
   sources = [
     "snapshot.h",
     "snapshot_android.cc",
     "snapshot_async.cc",
     "snapshot_async.h",
     "snapshot_aura.cc",
     "snapshot_export.h",
     "snapshot_ios.mm",
     "snapshot_mac.mm",
-    "snapshot_win.cc",
-    "snapshot_win.h",
   ]
 
   defines = [ "SNAPSHOT_IMPLEMENTATION" ]
 
   deps = [
     "//base",
     "//skia",
     "//ui/base",
     "//ui/gfx",
     "//ui/gfx/geometry",
@@ skipping 47 matching lines @@
     deps += [
       "//ui/aura:test_support",
       "//ui/compositor",
       "//ui/compositor:test_support",
       "//ui/wm",
     ]
   } else {
     sources -= [ "snapshot_aura_unittest.cc" ]
   }
 }
-
-if (is_win) {
-  source_set("test_support") {
-    sources = [
-      "test/snapshot_desktop.h",
-      "test/snapshot_desktop_win.cc",
-    ]
-    deps = [
-      ":snapshot",
-    ]
-  }
-}