clang: Add a tool for MessageLoop refactoring

tools/clang/scripts/run_tool.py

Index: tools/clang/scripts/run_tool.py
diff --git a/tools/clang/scripts/run_tool.py b/tools/clang/scripts/run_tool.py
index 58a9a86570c6b3b203d5a0004ce56d04426db314..7190fbd16a799612fdab94dd5d3431820dfe21ef 100755
--- a/tools/clang/scripts/run_tool.py
+++ b/tools/clang/scripts/run_tool.py
@@ -315,19 +315,25 @@ def main(argv):
 
   if len(argv) == 3 and argv[2] == '--all':
     filenames = set(_GetFilesFromCompileDB(argv[1]))
+    editable_filenames = filenames
   else:
-    filenames = set(_GetFilesFromGit(argv[2:]))
+    all_filenames = set(_GetFilesFromGit(argv[2:]))
     # Filter out files that aren't C/C++/Obj-C/Obj-C++.
     extensions = frozenset(('.c', '.cc', '.m', '.mm'))
-    filenames = [f for f in filenames
+    filenames = [f for f in all_filenames
                  if os.path.splitext(f)[1] in extensions]
+    # Some files (e.g., headers) are not part of the compile database but can
+    # still be edited.
+    editable_extensions = frozenset(('.h', )) | extensions
+    editable_filenames = [f for f in all_filenames
+                          if os.path.splitext(f)[1] in editable_extensions]
   dispatcher = _CompilerDispatcher(argv[0], argv[1], filenames)
   dispatcher.Run()
   # Filter out edits to files that aren't in the git repository, since it's not
   # useful to modify files that aren't under source control--typically, these
   # are generated files or files in a git submodule that's not part of Chromium.
   _ApplyEdits({k : v for k, v in dispatcher.edits.iteritems()
-                    if os.path.realpath(k) in filenames},
+                    if os.path.realpath(k) in editable_filenames},
               clang_format_diff_path)
   if dispatcher.failed_count != 0:
     return 2