Update from https://crrev.com/303153

build/gyp_chromium

Index: build/gyp_chromium
diff --git a/build/gyp_chromium b/build/gyp_chromium
index 326919c08cbe942e7b57e9a3ac88334841040122..ad2796b114030fa66ebb5cd575b5163855adca11 100755
--- a/build/gyp_chromium
+++ b/build/gyp_chromium
@@ -178,6 +178,9 @@ def additional_include_files(supplemental_files, args=[]):
     if os.path.realpath(path) not in specified_includes:
       result.append(path)
 
+  if os.environ.get('GYP_INCLUDE_FIRST') != None:
+    AddInclude(os.path.join(chrome_src, os.environ.get('GYP_INCLUDE_FIRST')))
+
   # Always include common.gypi.
   AddInclude(os.path.join(script_dir, 'common.gypi'))
 
@@ -185,6 +188,9 @@ def additional_include_files(supplemental_files, args=[]):
   for supplement in supplemental_files:
     AddInclude(supplement)
 
+  if os.environ.get('GYP_INCLUDE_LAST') != None:
+    AddInclude(os.path.join(chrome_src, os.environ.get('GYP_INCLUDE_LAST')))
+
   return result