Instrumented libraries: add a hook to download pre-built binaries.

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.
 #
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   # Pull the mojo_shell binary, used for mojo development
   {
     'name': 'download_mojo_shell',
     'pattern': '',
     'action': [ 'python',
                 'src/third_party/mojo/src/mojo/public/tools/download_shell_binary.py',
                 '--tools-directory=../../../../../../tools',
               ],
   },
   {
+    # 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'],
+  },
+  {
     # 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
     # 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',
     ],
   },
 ]