Fix mojo bindings generator error message printing

This change splits the print statement in the imports vs deps check
function into three separate ones, as well as prints the correct filename
instead of the first one in the list.

Change-Id: I81010efa46eeab37847d90df5574cdf34ff4b83f
Reviewed-on: https://chromium-review.googlesource.com/c/1316727
Commit-Queue: Oksana Zhuravlova <oksamyt@chromium.org>
Reviewed-by: Ken Rockot <rockot@google.com>
Cr-Commit-Position: refs/heads/master@{#605444}

mojo/public/tools/bindings/mojom_bindings_generator.py

@@ -370,9 +370,11 @@ def _VerifyImportDeps(args, __):
         args.gen_dir + "/", 1)[1]
       full_target_name = "//" + target_prefix_without_gen_dir.rsplit(
         "/", 1)[0] + ":" + target_name
-      print ">>> File \n\t%s\nfrom target \n\t%s\nis missing dependencies " + \
-        "for the following imports:\n\t%s" % (args.filename[0], \
-        full_target_name, list(mojom_imports.difference(sources)))
+
+      print ">>> File \"%s\"" % (filename)
+      print ">>> from target \"%s\"" % (full_target_name)
+      print ">>> is missing dependencies for the following imports:\n%s" % \
+        list(mojom_imports.difference(sources))
       sys.exit(1)
 
     source_filename, _ = os.path.splitext(rel_path.relative_path())