Encode all grit outputs in .gn files

extensions/BUILD.gn

Index: extensions/BUILD.gn
diff --git a/extensions/BUILD.gn b/extensions/BUILD.gn
index 47b4769936984dd29f51e03a99287d8639908e2b..945d1c1039a66f100639d9ad1d25cdc21945b8be 100644
--- a/extensions/BUILD.gn
+++ b/extensions/BUILD.gn
@@ -16,10 +16,18 @@ group("extensions_resources") {
 #              (exntensions_resources action)
 grit("extensions_resources_grd") {
   source = "extensions_resources.grd"
+  outputs = [
+    "grit/extensions_resources.h",
+    "extensions_resources.pak",
+  ]
 }
 
 # GYP version: extensions/extensions_resources.gyp:extensions_resources
 #              (exntensions_renderer_resources action)
 grit("extensions_renderer_resources") {
   source = "renderer/resources/extensions_renderer_resources.grd"
+  outputs = [
+    "grit/extensions_renderer_resources.h",
+    "extensions_renderer_resources.pak",
+  ]
 }