Enabling 'gn check' on webrtc/sdk

BUG=webrtc:7499

Review-Url: https://codereview.webrtc.org/2818433003
Cr-Commit-Position: refs/heads/master@{#17805}

webrtc/sdk/android/src/jni/DEPS

@@ -5,4 +5,5 @@ include_rules = [
   "+webrtc/modules/utility/include/jvm_android.h",
   "+webrtc/modules/video_coding/utility/vp8_header_parser.h",
   "+webrtc/pc",
+  "+webrtc/system_wrappers/include/field_trial_default.h",
 ]

webrtc/sdk/android/src/jni/peerconnection_jni.cc

@@ -74,7 +74,10 @@
 #include "webrtc/sdk/android/src/jni/jni_helpers.h"
 #include "webrtc/sdk/android/src/jni/native_handle_impl.h"
 #include "webrtc/sdk/android/src/jni/rtcstatscollectorcallbackwrapper.h"
-#include "webrtc/system_wrappers/include/field_trial_default.h"
+// Adding 'nogncheck' to disable the gn include headers check.
+// We don't want to depend on 'system_wrappers:field_trial_default' because
+// clients should be able to provide their own implementation.
+#include "webrtc/system_wrappers/include/field_trial_default.h" // nogncheck
 #include "webrtc/system_wrappers/include/logcat_trace_context.h"
 #include "webrtc/system_wrappers/include/trace.h"
 #include "webrtc/voice_engine/include/voe_base.h"