gn2bp: remove unused third_party deps handling

This was not useful for the cronet build, as we have not remapped
third_party deps into //gn (unlike perfetto).

We probably do want something similar for builtin_deps (like pass
builtin_deps into the GnParser constructor) to prevent static_library
dependencies to circumvent replaced dependencies via builtin_deps.

Test: //components/cronet/android:cronet
Change-Id: I77ed99eb14618a478281b9be025cf9d384066ddb
diff --git a/tools/gn2bp/gn_utils.py b/tools/gn2bp/gn_utils.py
index 2f45c44..fd8bc75 100644
--- a/tools/gn2bp/gn_utils.py
+++ b/tools/gn2bp/gn_utils.py
@@ -217,21 +217,6 @@
     target.toolchain = desc.get('toolchain', None)
     self.all_targets[gn_target_name] = target
 
-    # TODO: determine if below comment should apply for cronet builds in Android.
-    # We should never have GN targets directly depend on buidtools. They
-    # should hop via //gn:xxx, so we can give generators an opportunity to
-    # override them.
-    # Specifically allow targets to depend on libc++ and libunwind.
-    if not any(match in gn_target_name for match in ['libc++', 'libunwind']):
-      assert (not gn_target_name.startswith('//buildtools'))
-
-
-    # Don't descend further into third_party targets. Genrators are supposed
-    # to either ignore them or route to other externally-provided targets.
-    if gn_target_name.startswith('//gn'):
-      target.is_third_party_dep_ = True
-      return target
-
     proto_target_type, proto_desc = self.get_proto_target_type(gn_desc, gn_target_name)
     if proto_target_type is not None:
       self.proto_libs[target.name] = target