Fix Windows build, add Sandbox implementation.

tools/gn/secondary/third_party/angle/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.
 
 # This config is applied to internal Angle targets (not pushed to dependents).
 config("internal_config") {
   include_dirs = [
     "include",
     "src",
   ]
@@ skipping 550 matching lines @@
       "src/libEGL/resource.h",
     ]
 
     configs -= [ "//build/config/compiler:chromium_code" ]
     configs += [
       ":internal_config",
       "//build/config/compiler:no_chromium_code",
     ]
 
     if (is_debug) {
-      defines += [ "ANGLE_ENABLE_PERF" ]
+      defines = [ "ANGLE_ENABLE_PERF" ]
     }
 
     include_dirs = [ "src/libGLESv2" ]
     libs = [ "d3d9.lib" ]
 
     deps = [
       ":commit_id",
       ":includes",
       ":libGLESv2",
     ]
   }
 }  # is_win