Support script response files in GN.

components/domain_reliability/BUILD.gn

Index: components/domain_reliability/BUILD.gn
diff --git a/components/domain_reliability/BUILD.gn b/components/domain_reliability/BUILD.gn
index add26b47d25a7172ae08bf371dafcef85a015ca0..7b937e2ee650cb5b586e0e50172cd445faef094b 100644
--- a/components/domain_reliability/BUILD.gn
+++ b/components/domain_reliability/BUILD.gn
@@ -14,24 +14,53 @@ baked_in_configs_gypi = exec_script("//build/gypi_to_gn.py",
                                     [ rebase_path("baked_in_configs.gypi") ],
                                     "scope",
                                     [ "baked_in_configs.gypi" ])
+
+# The config file names in the .gypi are relative to "//components".
 baked_in_configs =
-    rebase_path(baked_in_configs_gypi.baked_in_configs, "domain_reliability")
+    rebase_path(baked_in_configs_gypi.baked_in_configs, ".", "//components")
 
-action("bake_in_configs") {
-  visibility = [ ":*" ]
-  script = "bake_in_configs.py"
+# TODO(brettw) enable once GN supports response_file_contents for actions.
+if (false) {
+  action("bake_in_configs") {
+    visibility = [ ":*" ]
+    script = "bake_in_configs.py"
 
-  inputs = baked_in_configs
-  outputs = [
-    "$target_gen_dir/baked_in_configs.cc",
-  ]
+    inputs = baked_in_configs
+    output_file = "$target_gen_dir/baked_in_configs.cc"
+    outputs = [
+      output_file,
+    ]
+
+    # The JSON file list is too long for the command line on Windows, so put
+    # them in a response file.
+    response_file_contents = rebase_path(inputs, root_build_dir)
+    args = [
+      "--file-list",
+      "{{response_file_name}}",
+      "--output",
+      rebase_path(output_file, root_build_dir),
+    ]
+  }
+} else {
+  action("bake_in_configs") {
+    visibility = [ ":*" ]
+    script = "bake_in_configs.py"
+
+    inputs = baked_in_configs
+    output_file = "$target_gen_dir/baked_in_configs.cc"
+    outputs = [
+      output_file,
+    ]
 
-  # The actual list of JSON files will overflow the command line length limit
-  # on Windows, so pass the name of the .gypi file and bake_in_configs.py will
-  # read the filenames out of it manually.
-  args = [ rebase_path("//components", root_build_dir) ] +
-         [ rebase_path("baked_in_configs.gypi", root_build_dir) ] +
-         rebase_path(outputs, root_build_dir)
+    # The actual list of JSON files will overflow the command line length limit
+    # on Windows, so pass the name of the .gypi file and bake_in_configs.py will
+    # read the filenames out of it manually.
+    args = [
+      "--gypi-file=" + rebase_path("baked_in_configs.gypi", root_build_dir),
+      "--gypi-relative-to=" + rebase_path("//components", root_build_dir),
+      "--output=" + rebase_path(output_file, root_build_dir),
+    ]
+  }
 }
 
 component("domain_reliability") {