[cr tool] Make context implicit

tools/cr/cr/actions/gyp.py

 # Copyright 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.
 
 """A module to add gyp support to cr."""
 
 import cr
 
 
 class GypPrepareOut(cr.PrepareOut):
   """A prepare action that runs gyp whenever you select an output directory."""
 
   ENABLED = cr.Config.From(
       GYP_GENERATORS='ninja',
       GYP_GENERATOR_FLAGS='output_dir={CR_OUT_BASE} config={CR_BUILDTYPE}',
   )
 
-  def Prepare(self, context):
-    if context.verbose >= 1:
-      print context.Substitute('Invoking gyp with {GYP_GENERATOR_FLAGS}')
+  def Prepare(self):
+    if cr.context.verbose >= 1:
+      print cr.context.Substitute('Invoking gyp with {GYP_GENERATOR_FLAGS}')
     cr.Host.Execute(
-        context,
         '{CR_SRC}/build/gyp_chromium',
         '--depth={CR_SRC}',
         '--check'
     )