Add a recipe to identify culprits for chromium compile failures.

scripts/slave/recipe_modules/findit/api.py

Index: scripts/slave/recipe_modules/findit/api.py
diff --git a/scripts/slave/recipe_modules/findit/api.py b/scripts/slave/recipe_modules/findit/api.py
new file mode 100644
index 0000000000000000000000000000000000000000..9809b0223e16d635d376d2bfcaccd2cf221964b8
--- /dev/null
+++ b/scripts/slave/recipe_modules/findit/api.py
@@ -0,0 +1,39 @@
+# Copyright 2015 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.
+
+from recipe_engine import recipe_api
+
+
+class FinditApi(recipe_api.RecipeApi):
+
+  def get_files_affected_by_revision(self, revision, repo_dir=''):
+    """Returns the files changed by the given revision.
+
+    Args:
+      revision (str): the git hash of a commit.
+      repo_dir (str): the relative path to the checkout directory.
+    """
+    if repo_dir:
+      cwd = self.m.path['checkout']
+    else:
+      cwd = self.m.path['checkout'].join(repo_dir)

[iannucci, 2015/11/18 03:57:53]

is this if/else backwards?

Does it make sense to just get rid of the default argument for repo_dir?

[stgao, 2015/11/19 22:06:33]

Changed input parameter to "solution_name" and derive the repo dir from it.

+
+    previous_revision = '%s~1' % revision
+    step_result = self.m.git('diff', previous_revision, revision, '--name-only',

[iannucci, 2015/11/18 03:57:54]

I think 

  revision+"~1"

is possibly clearer and shorter than previous_revision... but maybe that's just
me :)

[stgao, 2015/11/19 22:06:33]

Done.

+                             name='git diff to analyze commit',
+                             stdout=self.m.raw_io.output(),
+                             cwd=cwd,
+                             step_test_data=lambda:
+                             self.m.raw_io.test_api.stream_output('foo.cc'))
+
+    paths = step_result.stdout.split()
+    if repo_dir:
+      paths = [self.m.path.join(repo_dir, path) for path in paths]
+    if self.m.platform.is_win:
+      # Looks like "analyze" wants POSIX slashes even on Windows (since git
+      # uses that format even on Windows).
+      paths = [path.replace('\\', '/') for path in paths]
+
+    step_result.presentation.logs['files'] = paths
+    return paths