gn: Allow users to set 'check_includes' in action_foreach().

tools/gn/action_target_generator.h

Index: tools/gn/action_target_generator.h
diff --git a/tools/gn/action_target_generator.h b/tools/gn/action_target_generator.h
index 3c8b5a8ef68eb7f05cdacafb26c1c257a3539612..7bfb141a29018f1cd50069ef6e1c6f640558c826 100644
--- a/tools/gn/action_target_generator.h
+++ b/tools/gn/action_target_generator.h
@@ -25,6 +25,7 @@ class ActionTargetGenerator : public TargetGenerator {
   bool FillScript();
   bool FillScriptArgs();
   bool FillDepfile();
+  bool FillCheckIncludes();

[cjhopman, 2015/01/30 23:04:46]

If we are checking includes for every target type, we should probably just have
FillCheckIncludes in TargetGenerator and call it in TargetGenerator::Run().

Another option is to only check includes for binary targets.

I don't know which of those two approaches would be better.

 
   // Checks for errors in the outputs variable.
   bool CheckOutputs();