Enforce correct mime-type on some files formats (especially images)....

PRESUBMIT.py

Index: PRESUBMIT.py
===================================================================
--- PRESUBMIT.py	(revision 19268)
+++ PRESUBMIT.py	(working copy)
@@ -37,6 +37,8 @@
       input_api, output_api))
   results.extend(input_api.canned_checks.CheckChangeSvnEolStyle(
       input_api, output_api, sources))
+  results.extend(input_api.canned_checks.CheckSvnForCommonMimeTypes(
+      input_api, output_api))
   return results
 
 
@@ -56,6 +58,8 @@
       input_api, output_api))
   results.extend(input_api.canned_checks.CheckChangeSvnEolStyle(
       input_api, output_api, sources))
+  results.extend(input_api.canned_checks.CheckSvnForCommonMimeTypes(
+      input_api, output_api))
   # Make sure the tree is 'open'.
   # TODO(maruel): Run it in a separate thread to parallelize checks?
   results.extend(CheckTreeIsOpen(input_api, output_api,