Add a stale .pyc cleanup step before running gyp

DEPS

 # This file is used to manage the dependencies of the Chromium src repo. It is
 # used by gclient to determine what version of each dependency to check out, and
 # where.
 #
 # For more information, please refer to the official documentation:
 #   https://sites.google.com/a/chromium.org/dev/developers/how-tos/get-the-code
 #
 # When adding a new dependency, please update the top-level .gitignore file
 # to list the dependency's destination directory.
 #
@@ skipping 729 matching lines @@
               ],
   },
   {
     # Pull sanitizer-instrumented third-party libraries if requested via
     # GYP_DEFINES.
     'name': 'instrumented_libraries',
     'pattern': '\\.sha1',
     'action': ['python', 'src/third_party/instrumented_libraries/scripts/download_binaries.py'],
   },
   {
+    # Ensure that while generating dependencies lists in .gyp files we don't accidentally

[scottmg, 2015/06/12 22:58:25]

nit; Wrap at 80 col since there's nothing preventing it here.

[mnaganov (inactive), 2015/06/12 23:26:17]

Done.

+    # reference any .pyc files whose corresponding .py files have already been deleted.
+    'name': 'remove_stale_pyc_files_for_gyp',

[scottmg, 2015/06/12 22:58:25]

Probably just 'remove_stale_pyc_files' is better.

[mnaganov (inactive), 2015/06/12 23:26:17]

Done.

+    'pattern': '.',
+    'action': [
+        'python',
+        'src/tools/remove_stale_pyc_files.py',
+        'src/android_webview/tools',
+        'src/gpu/gles2_conform_support',
+        'src/ppapi',
+        'src/printing',
+        'src/third_party/closure_compiler/build',
+        'src/tools',
+    ],

[scottmg, 2015/06/12 22:58:25]

I was worried this would be kind of slow, but on Windows it's not that bad:

tim cmd /c python tools\remove_stale_pyc_files.py android_webview/tools
gpu/gles2_conform_support ppapi printing third_party/closure_compiler/build
tools
real: 0m0.453s

(Doing '.' on the other hand takes 18s, so that's no good.)

[mnaganov (inactive), 2015/06/12 23:26:17]

RemoveAllStalePycFiles doesn't skip output dirs, and third_party dirs can also
be quite big (e.g. layout test results). It may be possible to parallelize this
task, but that's not easy due to recursive nature of the traversal.

+  },
+  {
     # A change to a .gyp, .gypi, or to GYP itself should run the generator.
     'name': 'gyp',
     'pattern': '.',
     'action': ['python', 'src/build/gyp_chromium'],
   },
   {
     # Verify committers' ~/.netc, gclient and git are properly configured for
     # write access to the git repo. To be removed sometime after Chrome to git
     # migration completes (let's say Sep 1 2014).
     'name': 'check_git_config',
     'pattern': '.',
     'action': [
         'python',
         'src/tools/check_git_config.py',
         '--running-as-hook',
     ],
   },
   {
     # Ensure that we don't accidentally reference any .pyc files whose

[scottmg, 2015/06/12 22:58:25]

Seems unnecessary to do this here too?

[mnaganov (inactive), 2015/06/12 23:26:17]

Right. I guess, nobody deletes .py files in hooks.

     # corresponding .py files have already been deleted.
     'name': 'remove_stale_pyc_files',
     'pattern': 'src/tools/.*\\.py',
     'action': [
         'python',
         'src/tools/remove_stale_pyc_files.py',
         'src/tools',
     ],
   },
 ]