Mojo C++ bindings: switch device/nfc mojom target to use STL/WTF types.

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

Index: third_party/WebKit/Source/modules/nfc/NFC.cpp
diff --git a/third_party/WebKit/Source/modules/nfc/NFC.cpp b/third_party/WebKit/Source/modules/nfc/NFC.cpp
index 37382c9308663ed399d8fc6b31535490cb9ac2cc..87fa30cbc5c1c6e710cf418c240726da319528ce 100644
--- a/third_party/WebKit/Source/modules/nfc/NFC.cpp
+++ b/third_party/WebKit/Source/modules/nfc/NFC.cpp
@@ -131,7 +131,7 @@ struct TypeConverter<NFCRecordPtr, WTF::String> {
     record->record_type = NFCRecordType::TEXT;
     record->media_type = kPlainTextMimeType;
     record->media_type.append(kCharSetUTF8);
-    record->data = mojo::WTFArray<uint8_t>::From(string);
+    record->data = mojo::WTFArray<uint8_t>::From(string).PassStorage();
     return record;
   }
 };
@@ -142,7 +142,7 @@ struct TypeConverter<NFCRecordPtr, blink::DOMArrayBuffer*> {
     NFCRecordPtr record = NFCRecord::New();
     record->record_type = NFCRecordType::OPAQUE_RECORD;
     record->media_type = kOpaqueMimeType;
-    record->data = mojo::WTFArray<uint8_t>::From(buffer);
+    record->data = mojo::WTFArray<uint8_t>::From(buffer).PassStorage();

[haraken, 2016/11/12 01:35:41]

Would you help me understand what PassStorage is doing? i.e., when do we need to
use PassStorage?

[yzshen1, 2016/11/14 17:10:42]

Because with this CL, record->data's type becomes WTF::Vector<uint8_t>. In order
to convert a mojo::WTFArray<uint8_t> to that, we need to use PassStorage().

You might ask: why are we still using mojo::WTFArray<> at all? That is because
we have a TypeConverter defined to convert from blink::DOMArrayBuffer to
WTFArray. I am a little reluctant to change that to a conversion function from
blink::DOMArrayBuffer to WTF::Vector in this CL (which is supposed to be a
mechanical change).

[haraken, 2016/11/14 18:38:30]

Thanks, makes sense.

     return record;
   }
 };
@@ -151,8 +151,7 @@ template <>
 struct TypeConverter<NFCMessagePtr, WTF::String> {
   static NFCMessagePtr Convert(const WTF::String& string) {
     NFCMessagePtr message = NFCMessage::New();
-    message->data = mojo::WTFArray<NFCRecordPtr>::New(1);
-    message->data[0] = NFCRecord::From(string);
+    message->data.append(NFCRecord::From(string));
     return message;
   }
 };
@@ -223,14 +222,14 @@ struct TypeConverter<NFCRecordPtr, blink::NFCRecord> {
         break;
     }
 
-    recordPtr->data = mojo::WTFArray<uint8_t>::From(record.data());
-
+    auto recordData = mojo::WTFArray<uint8_t>::From(record.data());
     // If JS object cannot be converted to uint8_t array, return null,
     // interrupt NFCMessage conversion algorithm and reject promise with
     // SyntaxError exception.
-    if (recordPtr->data.is_null())
+    if (recordData.is_null())
       return nullptr;
 
+    recordPtr->data = recordData.PassStorage();
     return recordPtr;
   }
 };
@@ -248,7 +247,6 @@ struct TypeConverter<NFCMessagePtr, blink::NFCMessage> {
 
       messagePtr->data[i] = std::move(record);
     }
-    messagePtr->data = mojo::WTFArray<NFCRecordPtr>::From(message.data());

[haraken, 2016/11/12 01:35:41]

Why can we remove this?

[yzshen1, 2016/11/14 17:10:42]

Because line 243-250 does the same thing as line 251 (except that line 243-250
doesn't allow null element). Therefore, I kept the former.

     return messagePtr;
   }
 };
@@ -257,8 +255,7 @@ template <>
 struct TypeConverter<NFCMessagePtr, blink::DOMArrayBuffer*> {
   static NFCMessagePtr Convert(blink::DOMArrayBuffer* buffer) {
     NFCMessagePtr message = NFCMessage::New();
-    message->data = mojo::WTFArray<NFCRecordPtr>::New(1);
-    message->data[0] = NFCRecord::From(buffer);
+    message->data.append(NFCRecord::From(buffer));
     return message;
   }
 };
@@ -581,7 +578,7 @@ void NFC::OnConnectionError() {
   m_requests.clear();
 }
 
-void NFC::OnWatch(mojo::WTFArray<uint32_t> ids, mojom::NFCMessagePtr) {
+void NFC::OnWatch(const WTF::Vector<uint32_t>& ids, mojom::NFCMessagePtr) {
   // TODO(shalamov): Not implemented.
 }