PPAPI: Make API changes w/o IDL changes Warnings if generators have changed

We frequently run in to the situation where we change the generators
which causes some real (but usually minor) change in header files, even
though the IDL is unchanged. We should just warn in that situation, so that
developers can use the CQ for these kind of generator changes.

BUG=

Review URL: https://chromiumcodereview.appspot.com/23620032

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@222190 0039d316-1c4b-4281-b951-d872f2087c98

ppapi/PRESUBMIT.py

@@ -159,6 +159,7 @@ def CheckChange(input_api, output_api):
   files = input_api.LocalPaths()
   h_files = []
   idl_files = []
+  generators_changed = False
 
   # Find all relevant .h and .idl files.
   for filename in files:
@@ -166,8 +167,10 @@ def CheckChange(input_api, output_api):
     name_parts = name.split(os.sep)
     if name_parts[0:2] == ['ppapi', 'c'] and ext == '.h':
       h_files.append('/'.join(name_parts[2:]))
-    if name_parts[0:2] == ['ppapi', 'api'] and ext == '.idl':
+    elif name_parts[0:2] == ['ppapi', 'api'] and ext == '.idl':
       idl_files.append('/'.join(name_parts[2:]))
+    elif name_parts[0:2] == ['ppapi', 'generators']:
+      generators_changed = True
 
   # Generate a list of all appropriate *.h and *.idl changes in this CL.
   both = h_files + idl_files
@@ -247,10 +250,20 @@ def CheckChange(input_api, output_api):
             long_text='\n'.join(missing_dev)))
 
   if missing_stable:
-    results.append(
-        output_api.PresubmitError(
-            'Missing PPAPI IDL for stable interface:',
-            long_text='\n'.join(missing_stable)))
+    # It might be okay that the header changed without a corresponding IDL
+    # change. E.g., comment indenting may have been changed. Treat this as a
+    # warning.
+    if generators_changed:
+      results.append(
+          output_api.PresubmitPromptWarning(
+              'Missing PPAPI IDL for stable interface (due to change in ' +
+              'generators?):',
+              long_text='\n'.join(missing_stable)))
+    else:
+      results.append(
+          output_api.PresubmitError(
+              'Missing PPAPI IDL for stable interface:',
+              long_text='\n'.join(missing_stable)))
 
   # Verify all *.h files match *.idl definitions, use:
   #   --test to prevent output to disk