Remove remaining legacy SplitString calls.

tools/gn/runtime_deps.cc

Index: tools/gn/runtime_deps.cc
diff --git a/tools/gn/runtime_deps.cc b/tools/gn/runtime_deps.cc
index e905d7ca45d54227be4e12fcd928883857d2ccf0..f6441e8cd113b4ddd9ac96ec12e40904a782ba36 100644
--- a/tools/gn/runtime_deps.cc
+++ b/tools/gn/runtime_deps.cc
@@ -241,12 +241,10 @@ bool WriteRuntimeDepsFilesIfNecessary(const Builder& builder, Err* err) {
   }
   load_trace.Done();
 
-  std::vector<std::string> lines;
-  base::SplitString(list_contents, '\n', &lines);
-
   SourceDir root_dir("//");
   Label default_toolchain_label = builder.loader()->GetDefaultToolchain();
-  for (const auto& line : lines) {
+  for (const auto& line : base::SplitString(
+           list_contents, "\n", base::TRIM_WHITESPACE, base::SPLIT_WANT_ALL)) {
     if (line.empty())
       continue;
     Label label = Label::Resolve(root_dir, default_toolchain_label,