Tighten DEPS in ios/

The DEPS checker implicitly allow all files in a subdirectory of src/
to include any other file in the same directory. This meant that any
file in ios/ could include any other file except when explicitly
forbidden.

This CL change this by disabling all inclusion of files from ios/ at
the root level, leaving the dependency decision to the individual
subdirectories.

BUG=None

Review URL: https://codereview.chromium.org/952633002

Cr-Commit-Position: refs/heads/master@{#317816}
diff --git a/ios/DEPS b/ios/DEPS
new file mode 100644
index 0000000..2ee6925
--- /dev/null
+++ b/ios/DEPS
@@ -0,0 +1,8 @@
+include_rules = [
+  # The subdirectories in ios/ will manually allow their own include
+  # directories in ios/ so we disallow all of them.
+  "-ios",
+
+  # For unit tests.
+  "+third_party/ocmock",
+]