Avoid rebuilding remoting host every time gyp runs

remoting/remoting.gyp

 # Copyright (c) 2012 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.
 
 {
   'variables': {
     'chromium_code': 1,
 
     # Set this to run the jscompile checks after building the webapp.
     'run_jscompile%': 0,
@@ skipping 41 matching lines @@
         'host_plugin_extension': 'arm.so',
         'host_plugin_prefix': 'lib',
       }],
       ['os_posix == 1 and OS != "mac" and target_arch == "mipsel"', {
         'host_plugin_extension': 'mipsel.so',
         'host_plugin_prefix': 'lib',
       }],
       ['OS=="win"', {
         'host_plugin_extension': 'dll',
         'host_plugin_prefix': '',
-        # Use auto-generated CLSIDs to make sure that the newly installed COM
-        # classes will be used during/after upgrade even if there are old
-        # instances running already.
-        # The parameter at the end is ignored, but needed to make sure that the
-        # script will be invoked separately for each CLSID. Otherwise GYP will
-        # reuse the value returned by the first invocation of the script.
+
+        # Each CLSID is a hash of the current version string salted with an
+        # arbitrary GUID. This ensures that the newly installed COM classes will
+        # be used during/after upgrade even if there are old instances running
+        # already.
+        # The IDs are not random to avoid rebuilding host when it's not
+        # necessary.
         'daemon_controller_clsid':
-            '<!(python -c "import uuid; print uuid.uuid4()" 1)',
+            '<!(python -c "import uuid; print uuid.uuid5(uuid.UUID(\'655bd819-c08c-4b04-80c2-f160739ff6ef\'), \'<(version_full)\')")',
         'rdp_desktop_session_clsid':
-            '<!(python -c "import uuid; print uuid.uuid4()" 2)',
+            '<!(python -c "import uuid; print uuid.uuid5(uuid.UUID(\'6a7699f0-ee43-43e7-aa30-a6738f9bd470\'), \'<(version_full)\')")',
       }],
     ],
     'remoting_locales': [
       'ar', 'bg', 'ca', 'cs', 'da', 'de', 'el', 'en', 'en-GB', 'es',
       'es-419', 'et', 'fi', 'fil', 'fr', 'he', 'hi', 'hr', 'hu', 'id',
       'it', 'ja', 'ko', 'lt', 'lv', 'nb', 'nl', 'pl', 'pt-BR', 'pt-PT',
       'ro', 'ru', 'sk', 'sl', 'sr', 'sv', 'th', 'tr', 'uk', 'vi',
       'zh-CN', 'zh-TW',
     ],
     'remoting_locale_files': [
@@ skipping 545 matching lines @@
         'protocol/v2_authenticator.h',
         'protocol/video_reader.cc',
         'protocol/video_reader.h',
         'protocol/video_stub.h',
         'protocol/video_writer.cc',
         'protocol/video_writer.h',
       ],
     },  # end of target 'remoting_protocol'
   ],  # end of targets
 }