systrace: Release NOTICE file.

Change-Id: I5ad19b219ca2c6699c3f467266e9a4159a716b86
diff --git a/build/tools.atree b/build/tools.atree
index 78da7fc..c96926d 100644
--- a/build/tools.atree
+++ b/build/tools.atree
@@ -177,6 +177,7 @@
 external/chromium-trace/style.css      tools/systrace/style.css
 external/chromium-trace/LICENSE        tools/systrace/LICENSE
 external/chromium-trace/AUTHORS        tools/systrace/AUTHORS
+external/chromium-trace/NOTICE         tools/systrace/NOTICE
 
 # Misspelling databases for lint
 sdk/files/typos                        tools/support