Reland "Add check_deps rules in DEPS files."

Relanding https://codereview.webrtc.org/1796413002/
without the change to the openmax_dl include path
(which broke downstream code).

TBR=tommi@webrtc.org
BUG=webrtc:5623
TESTED=Passing runs using:
buildtools/checkdeps/checkdeps.py --root=. talk
buildtools/checkdeps/checkdeps.py --root=. webrtc

Review URL: https://codereview.webrtc.org/1804333002 .

Cr-Commit-Position: refs/heads/master@{#12031}

webrtc/examples/DEPS

@@ -0,0 +1,8 @@
+include_rules = [
+  "+webrtc/api",
+  "+webrtc/base",
+  "+webrtc/media",
+  "+webrtc/modules/audio_device",
+  "+webrtc/modules/video_capture",
+  "+webrtc/p2p",
+]