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

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

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "modules/nfc/NFC.h"
 
 #include "bindings/core/v8/ScriptPromiseResolver.h"
 #include "bindings/core/v8/V8ArrayBuffer.h"
 #include "bindings/core/v8/V8StringResource.h"
 #include "core/dom/DOMArrayBuffer.h"
@@ skipping 561 matching lines @@
   }
   return message_size;
 }
 
 }  // namespace
 
 NFC::NFC(LocalFrame* frame)
     : PageVisibilityObserver(frame->GetPage()),
       ContextLifecycleObserver(frame->GetDocument()),
       client_(this) {
+  String error_message;
+
+  // Only connect to NFC if we are in a context that supports it.
+  if (!IsSupportedInContext(GetExecutionContext(), error_message))
+    return;
+
   frame->GetInterfaceProvider()->GetInterface(mojo::MakeRequest(&nfc_));
   nfc_.set_connection_error_handler(ConvertToBaseCallback(
       WTF::Bind(&NFC::OnConnectionError, WrapWeakPersistent(this))));
   nfc_->SetClient(client_.CreateInterfacePtrAndBind());
 }
 
 NFC* NFC::Create(LocalFrame* frame) {
   NFC* nfc = new NFC(frame);
   return nfc;
 }
@@ skipping 191 matching lines @@
       MessageCallback* callback = it->value;
       ScriptState* script_state = callback->GetScriptState();
       DCHECK(script_state);
       ScriptState::Scope scope(script_state);
       NFCMessage nfc_message = ToNFCMessage(script_state, message);
       callback->handleMessage(nfc_message);
     }
   }
 }
 
-ScriptPromise NFC::RejectIfNotSupported(ScriptState* script_state) {
-  String error_message;
-  ExecutionContext* context = ExecutionContext::From(script_state);
+bool NFC::IsSupportedInContext(ExecutionContext* context,
+                               String& error_message) {
   if (!context->IsSecureContext(error_message)) {
-    return ScriptPromise::RejectWithDOMException(
-        script_state, DOMException::Create(kSecurityError, error_message));
+    return false;
   }
 
   // https://w3c.github.io/web-nfc/#security-policies
   // WebNFC API must be only accessible from top level browsing context.
   if (!ToDocument(context)->domWindow()->GetFrame() ||
       !ToDocument(context)->GetFrame()->IsMainFrame()) {
+    error_message = "Must be in a top-level browsing context";
+    return false;
+  }
+
+  return true;
+}
+
+ScriptPromise NFC::RejectIfNotSupported(ScriptState* script_state) {
+  String error_message;
+  if (!IsSupportedInContext(ExecutionContext::From(script_state),
+                            error_message)) {
     return ScriptPromise::RejectWithDOMException(
-        script_state,
-        DOMException::Create(kSecurityError,
-                             "Must be in a top-level browsing context."));
+        script_state, DOMException::Create(kSecurityError, error_message));
   }
 
   if (!nfc_) {
     return ScriptPromise::RejectWithDOMException(
         script_state, DOMException::Create(kNotSupportedError));
   }
 
   return ScriptPromise();
 }
 
@@ skipping 22 matching lines @@
 }
 
 DEFINE_TRACE(NFC) {
   PageVisibilityObserver::Trace(visitor);
   ContextLifecycleObserver::Trace(visitor);
   visitor->Trace(requests_);
   visitor->Trace(callbacks_);
 }
 
 }  // namespace blink