Jumbo for blink/core generated files as well (saving 8 CPU minutes)

build/config/jumbo.gni

Index: build/config/jumbo.gni
diff --git a/build/config/jumbo.gni b/build/config/jumbo.gni
index 4a5f22f4a94ee0d2937adbe6ef5088857679df44..364485cb49cb919b9a1fa8016f362f180a01b66a 100644
--- a/build/config/jumbo.gni
+++ b/build/config/jumbo.gni
@@ -66,6 +66,25 @@ template("jumbo_target") {
   invoker_sources = invoker.sources
   gen_target_dir = get_path_info(invoker_sources[0], "gen_dir")
   assert(excluded_sources != [] || true)  # Prevent "unused variable".
+
+  # Find the gen_target_dir directory with shortest path. Short paths
+  # are nice in themselves since they mean shorter error messages and
+  # fewer bytes to parse, but the currently deployed version of ninja
+  # also has a limitation where it only allows 32 path components in
+  # Windows.
+  # See https://crbug.com/738186 and
+  # https://github.com/ninja-build/ninja/issues/1161
+  foreach(source_file, invoker.sources) {
+    possibly_better_gen_target_dir = get_path_info(gen_target_dir, "dir")
+    possibly_better_gen_target_dir_2 =
+        get_path_info(possibly_better_gen_target_dir, "dir")
+    alt_gen_target_dir = get_path_info(source_file, "gen_dir")
+    if (alt_gen_target_dir == possibly_better_gen_target_dir ||
+        alt_gen_target_dir == possibly_better_gen_target_dir_2) {
+      gen_target_dir = alt_gen_target_dir
+    }
+  }
+
   assert(gen_target_dir != "")  # Prevent "unused variable".
 
   if (use_jumbo_build_for_target) {