Fix some TODOs in the yasm build.

The TODO about a system yasm is not longer necessary. We don't need to support this for Chrome developers. For Linux distros, Pawel has added an overlay to change the behavior.

The TODO about the output names is out-of-date. The new output location matches the names generated by the C compiler in the Chrome build.

Cr-Original-Commit-Position: refs/heads/master@{#393544}
Cr-Mirrored-Commit: 09869628d781a977987b65906856bd259e40dd9e
diff --git a/yasm_assemble.gni b/yasm_assemble.gni
index 1a84d51..feaba1f 100644
--- a/yasm_assemble.gni
+++ b/yasm_assemble.gni
@@ -94,7 +94,6 @@
 template("yasm_assemble") {
-  # TODO(ajwong): Support use_system_yasm.
   assert(defined(invoker.sources), "Need sources defined for $target_name")
   # Only depend on YASM on x86 systems. Force compilation of .asm files for
@@ -166,14 +165,8 @@
     # Output file.
-    #
-    # TODO(brettw) it might be nice if there was a source expansion for the
-    # path of the source file relative to the source root. Then we could
-    # exactly duplicate the naming and location of object files from the
-    # native build, which would be:
-    # "$root_out_dir/${target_name}.{{source_dir_part}}.$asm_obj_extension"
     outputs = [
-      "$target_out_dir/{{source_name_part}}.o",
+      "$target_out_dir/$source_set_name/{{source_name_part}}.o",
     args += [