[NFC] Only connect to NFC impl if ExecutionContext supports it

third_party/WebKit/Source/modules/nfc/NFC.h

Index: third_party/WebKit/Source/modules/nfc/NFC.h
diff --git a/third_party/WebKit/Source/modules/nfc/NFC.h b/third_party/WebKit/Source/modules/nfc/NFC.h
index 9ffb2c7209e3d2fcb9d1f8574128f4cbb939723d..fef5a5ac1ae5f0565da52b6dbbdd3284974673ed 100644
--- a/third_party/WebKit/Source/modules/nfc/NFC.h
+++ b/third_party/WebKit/Source/modules/nfc/NFC.h
@@ -65,6 +65,10 @@ class NFC final : public GarbageCollectedFinalized<NFC>,
   DECLARE_VIRTUAL_TRACE();
 
  private:
+  // Returns boolean indicating whether NFC is supported in |context|. If not,
+  // |error_message| gives a message indicating why not.
+  bool IsSupportedInContext(ExecutionContext*, String&);

[jochen (gone - plz use gerrit), 2017/05/15 05:34:55]

nit. should be String& error_message, as it's not obvious what that parameter is
otherwise

[blundell, 2017/05/15 07:27:55]

Done.

+
   // Returns promise with DOMException if feature is not supported
   // or when context is not secure. Otherwise, returns empty promise.
   ScriptPromise RejectIfNotSupported(ScriptState*);