[webnfc] Implement push method for Android nfc mojo service.

device/nfc/nfc.mojom

 // 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.
 
 module device.nfc;
 
 enum NFCErrorType {
   SECURITY,
   NOT_SUPPORTED,
   DEVICE_DISABLED,
   NOT_FOUND,
   INVALID_MESSAGE,
   OPERATION_CANCELLED,
   TIMER_EXPIRED,
   CANNOT_CANCEL,
   IO_ERROR
 };
 
 enum NFCRecordType {
   EMPTY,
   TEXT,
   URL,
   JSON,
   OPAQUE_RECORD
 };
 
 enum NFCPushTarget {
+  // The target of a push operation must be the NFC tag.
   TAG,
+  // The target of a push operation must be the NFC peer (device to device).
   PEER,
+  // The target of a push operation must be either NFC tag or peer.
   ANY
 };
 
 enum NFCWatchMode {
+  // Restricts scope of the watch operation. Only Web NFC messages must be
+  // used by matching algorithm.
   WEBNFC_ONLY,
+  // Allows performing watch operation for all NFC messages. For example, NFC
+  // tags with valid NDEF messages.
   ANY
 };
 
 struct NFCError {
   NFCErrorType error_type;
 };
 
 struct NFCRecord {
+  // The type of NFCRecord.
   NFCRecordType recordType;
+
+  // Represents the IANA media type of the NFCRecord data field.
   string? mediaType;
+
+  // Payload of the NFCRecord.
   array<uint8> data;
 };
 
 struct NFCMessage {
+  // The body of the NFCMessage is a collection of NFCRecord objects.
   array<NFCRecord> data;
+
+  // The |url| field is an ASCII serialized origin, optionally followed by a URL
+  // path. It represents Web NFC id, that can be used for matching Web NFC
+  // content with the filter specified by |url| field in NFCWatchOptions.
   string? url;
 };
 
 struct NFCPushOptions {
+  // The target of the push operation.
   NFCPushTarget target;
+
+  // The timeout for the push operation, in milliseconds.
   double timeout;
+
+  // If the property is true, the push operation will suspend active watchers
+  // until it's completion.

[dcheng, 2016/08/17 17:18:47]

Nit: its.

   bool ignoreRead;
 };
 
 struct NFCRecordTypeFilter {
   NFCRecordType recordType;
 };
 
 struct NFCWatchOptions {
+  // Defines filtering constraint for NFC messages with specified |url|.
   string? url;
+
+  // Defines filtering constraint for NFC records with specified record type.
   NFCRecordTypeFilter? recordFilter;
+
+  // Defines media type filtering constraint.
   string? mediaType;
+
+  // Defines mode of watch operation.
   NFCWatchMode mode;
 };
 
 interface NFC {
   // NFCClient interface is used to notify |client| when NFCMessage matches one
   // or more pending watch operations.
   SetClient(NFCClient client);
 
   // Pushes data to NFC device.
   // NFCPushOptions specify timeout and type of device where data should be
   // pushed. If timeout is defined and data is not pushed before timeout is
   // expired, callback with corresponding error is called.
   Push(NFCMessage message, NFCPushOptions? options) => (NFCError? error);
 
   // Cancels pending push request.
   CancelPush(NFCPushTarget target) => (NFCError? error);
 
   // Starts watching for nearby NFC devices with data that matches
-  // NFCWatchOptions filtering criteria. On success, watch ID is returned.
+  // NFCWatchOptions filtering criteria. On success, watch id is returned.
   Watch(NFCWatchOptions options) => (uint32 id, NFCError? error);
 
   // Cancels watch operation with provided id.
   CancelWatch (uint32 id) => (NFCError? error);
 
   // Cancels all watch operations.
   CancelAllWatches () => (NFCError? error);
 
   // Suspends all pending NFC operations. Could be used when web page
   // visibility or focus is lost.
   SuspendNFCOperations();
 
   // Resumes all suspended NFC operations.
   ResumeNFCOperations();
 };
 
 interface NFCClient {
   OnWatch(array<uint32> watchIDs, NFCMessage message);
 };