Hook up .d files and outputs to grit

build/secondary/tools/grit/grit_rule.gni

Index: build/secondary/tools/grit/grit_rule.gni
diff --git a/build/secondary/tools/grit/grit_rule.gni b/build/secondary/tools/grit/grit_rule.gni
index 86a155a7fb12e00bc2a473952dbf431b63f1e4ed..ef3e3d454bf16e43eff00256bc95ebc8b832f964 100644
--- a/build/secondary/tools/grit/grit_rule.gni
+++ b/build/secondary/tools/grit/grit_rule.gni
@@ -10,6 +10,23 @@
 #   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.
+#
 #   grit_flags (optional)
 #       List of strings containing extra command-line flags to pass to Grit.
 #
@@ -165,9 +182,6 @@ grit_info_script = "//tools/grit/grit_info.py"
 template("grit") {
   assert(defined(invoker.source),
          "\"source\" must be defined for the grit template $target_name")
-  assert(!defined(invoker.sources) && !defined(invoker.outputs),
-         "Neither \"sources\" nor \"outputs\" can be defined for the grit " +
-         "template $target_name")
 
   if (defined(invoker.resource_ids)) {
     resource_ids = invoker.resource_ids
@@ -195,25 +209,37 @@ template("grit") {
     grit_flags = []  # These are optional so default to empty list.
   }
 
-  grit_inputs_build_rel = exec_script(grit_info_script,
-    [ "--inputs", source_path, "-f", resource_ids] + grit_flags, "list lines")
-  # The inputs are relative to the current (build) directory, rebase to
-  # the current one.
-  grit_inputs = rebase_path(grit_inputs_build_rel, ".", root_build_dir) + [
-    grit_resource_id_file,
-  ]
-
-  grit_outputs_build_rel = exec_script(grit_info_script,
-    [ "--outputs", "$rebased_output_dir", source_path, "-f", resource_ids ] +
-    grit_flags,
-    "list lines")
-
-  # The names returned by grit are relative to the current (build) directory,
-  # but references to files in this template are expected to be relative to the
-  # invoking BUILD.gn file's directory. Make it absolute so there's no
-  # ambiguity.
-  grit_outputs = get_path_info(
-      rebase_path(grit_outputs_build_rel, ".", root_build_dir), "abspath")
+  grit_inputs = [ invoker.source ]
+
+  assert_files_flags = []
+  if (defined(invoker.outputs)) {
+    # If the declaration specified outputs, we want to make sure that they
+    # actually match what Grit is writing. We write the list to a file (some
+    # of the output lists are long enough to not fit on a Windows command line)
+    # and ask Grit to verify those are the actual outputs at runtime.
+    asserted_list_file = "$target_out_dir/${target_name}_expected_outputs.txt"
+    write_file(asserted_list_file,
+               rebase_path(invoker.outputs, root_build_dir, target_gen_dir))
+    assert_files_flags += [
+      "--assert-file-list=" + rebase_path(asserted_list_file, root_build_dir),
+    ]
+    grit_outputs = get_path_info(
+        rebase_path(invoker.outputs, ".", target_gen_dir),
+        "abspath")
+  } else {
+    # Ask Grit for the output list.
+    grit_outputs_build_rel = exec_script(grit_info_script,
+      [ "--outputs", "$rebased_output_dir", source_path, "-f", resource_ids ] +
+      grit_flags,
+      "list lines")
+
+    # The names returned by grit are relative to the current (build) directory,
+    # but references to files in this template are expected to be relative to
+    # the invoking BUILD.gn file's directory. Make it absolute so there's no
+    # ambiguity.
+    grit_outputs = get_path_info(
+        rebase_path(grit_outputs_build_rel, ".", root_build_dir), "abspath")
+  }
 
   # The config and the action below get this visibility son only the generated
   # source set can depend on them. The variable "target_name" will get
@@ -235,17 +261,21 @@ template("grit") {
     script = "//tools/grit/grit.py"
     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,
-    ] + grit_defines + grit_flags
+      "--depdir", ".",
+      "--depfile", rebase_path(depfile, root_build_dir),
+    ] + grit_defines + grit_flags + assert_files_flags
 
     visibility = target_visibility
 
+    deps = [ "//tools/grit:grit_sources" ]
     if (defined(invoker.deps)) {
-      deps = invoker.deps
+      deps += invoker.deps
     }
   }