perfetto: introduce base::optional

Change-Id: I6b01026f677b1b9d3225561feb558d93ed10a36b
diff --git a/Android.bp b/Android.bp
index 8bb0a4c..f6762ed 100644
--- a/Android.bp
+++ b/Android.bp
@@ -4483,6 +4483,7 @@
     "src/base/event.cc",
     "src/base/file_utils.cc",
     "src/base/metatrace.cc",
+    "src/base/optional_unittest.cc",
     "src/base/paged_memory.cc",
     "src/base/paged_memory_unittest.cc",
     "src/base/scoped_file_unittest.cc",