Landmine to ensure GN roll revert has effect everywhere.

TBR=machenbach@chromium.org

Bug: 736215
Change-Id: I30b49f478c8c6ba9a6507092924a6f05a5f6ea8e
No-Try: True
Reviewed-on: https://chromium-review.googlesource.com/544867Reviewed-by: Andrii Shyshkalov <tandrii@chromium.org>
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Andrii Shyshkalov <tandrii@chromium.org>
Cr-Commit-Position: refs/heads/master@{#481841}

build/get_landmines.py

@@ -74,6 +74,7 @@ def print_landmines():
     print 'Clobber to get past mojo gen build error (crbug.com/679607)'
   if platform() == 'win':
     print 'Clobber Windows to fix strange PCH-not-rebuilt errors.'
+  print 'CLobber all to fix GN breakage (crbug.com/736215)'
 
 def main():
   print_landmines()