Declare the package strong-mode clean.

R=rnystrom@google.com

Review URL: https://codereview.chromium.org//1946193005 .

.analysis_options

diff --git a/.analysis_options b/.analysis_options
new file mode 100644
index 0000000..a10d4c5
--- /dev/null
+++ b/.analysis_options
@@ -0,0 +1,2 @@
+analyzer:
+  strong-mode: true