Update the tracing grit GN rule

build/secondary/tools/grit/grit_rule.gni

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # Instantiate grit. This will produce a script target to run grit, and a
 # static library that compiles the .cc files.
 #
 # Parameters
 #
 #   source
 #       Path to .grd file.
 #
 #   outputs (optional)
 #       List of outputs from grit, relative to the target_gen_dir. If supplied,
 #       a call to Grit to compute the outputs can be skipped which will make
 #       GN run faster. Grit will verify at build time that this list is correct
 #       and will fail if there is a mismatch between the outputs specified by
 #       the .grd file and the outputs list here.
 #
 #       To get this list, you can look in the .grd file for
 #       <output filename="..." and put those filename here. The base directory
 #       of the list in Grit and the output list specified in the GN grit target
 #       are the same (the target_gen_dir) so you can generally copy the names
 #       exactly.
 #
 #       To get the list of outputs programatically, run:
 #           python tools/grit/grit_info.py --outputs . path/to/your.grd
 #       And strip the leading "./" from the output files.
 #
+#   defines (optional)
+#       Extra defines to pass to grit (on top of the global grit_defines list).
+#
 #   grit_flags (optional)
 #       List of strings containing extra command-line flags to pass to Grit.
 #
 #   resource_ids (optional)
 #     Path to a grit "firstidsfile". Default is
 #     //tools/gritsettings/resource_ids. Set to "" to use the value specified in
 #     the <grit> nodes of the processed files.
 #
 #   output_dir (optional)
 #     Directory for generated files.
@@ skipping 222 matching lines @@
     inputs = grit_inputs
     outputs = grit_outputs
     depfile = "$target_out_dir/${target_name}.d"
 
     args = [
       "-i", source_path, "build",
       "-f", resource_ids,
       "-o", rebased_output_dir,
       "--depdir", ".",
       "--depfile", rebase_path(depfile, root_build_dir),
-    ] + grit_defines + grit_flags + assert_files_flags
+    ] + grit_defines
+
+    # Add extra defines with -D flags.
+    if (defined(invoker.defines)) {
+      foreach (i, invoker.defines) {
+        args += [ "-D", i ]
+      }
+    }
+
+    args += grit_flags + assert_files_flags
 
     visibility = target_visibility
 
     deps = [ "//tools/grit:grit_sources" ]
     if (defined(invoker.deps)) {
       deps += invoker.deps
     }
   }
 
   # This is the thing that people actually link with, it must be named the
   # same as the argument the template was invoked with.
   source_set(target_name) {
     # Since we generate a file, we need to be run before the targets that
     # depend on us.
     sources = grit_outputs
 
     # Deps set on the template invocation will go on the grit script running
     # target rather than this library.
     deps = [ ":$grit_custom_target" ]
     direct_dependent_configs = [ ":$grit_config" ]
 
     if (defined(invoker.visibility)) {
       visibility = invoker.visibility
     }
     if (defined(invoker.output_name)) {
       output_name = invoker.output_name
     }
   }
 }