Allow multiple DataDecoderService receivers

DataDecoderService is currently set up to allow only a single client
pipe. This is reasonable for the out-of-process case in most production
environments. For the in-process case (in tests and on iOS) however, it
is possible and reasonable for a single instance to have multiple
DataDecoderService pipes connected to it.

This upgrades the lone Receiver to a ReceiverSet, allowing for multiple
clients.

Fixed: 1022313
Change-Id: Iaeea6e1b1316351da0b6f57ae4a432eed62b5575
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1903748
Reviewed-by: Robert Sesek <rsesek@chromium.org>
Commit-Queue: Ken Rockot <rockot@google.com>
Cr-Commit-Position: refs/heads/master@{#713566}

services/data_decoder/data_decoder_service.cc

@@ -32,14 +32,14 @@ DataDecoderService::DataDecoderService() = default;
 
 DataDecoderService::DataDecoderService(
     mojo::PendingReceiver<mojom::DataDecoderService> receiver) {
-  receiver_.Bind(std::move(receiver));
+  receivers_.Add(this, std::move(receiver));
 }
 
 DataDecoderService::~DataDecoderService() = default;
 
 void DataDecoderService::BindReceiver(
     mojo::PendingReceiver<mojom::DataDecoderService> receiver) {
-  receiver_.Bind(std::move(receiver));
+  receivers_.Add(this, std::move(receiver));
 }
 
 void DataDecoderService::BindImageDecoder(

services/data_decoder/data_decoder_service.h

@@ -9,7 +9,7 @@
 
 #include "base/macros.h"
 #include "mojo/public/cpp/bindings/pending_receiver.h"
-#include "mojo/public/cpp/bindings/receiver.h"
+#include "mojo/public/cpp/bindings/receiver_set.h"
 #include "services/data_decoder/public/mojom/bundled_exchanges_parser.mojom.h"
 #include "services/data_decoder/public/mojom/data_decoder_service.mojom.h"
 #include "services/data_decoder/public/mojom/image_decoder.mojom.h"
@@ -61,7 +61,9 @@ class DataDecoderService : public mojom::DataDecoderService {
       mojo::PendingReceiver<mojom::BleScanParser> receiver) override;
 #endif  // OS_CHROMEOS
 
-  mojo::Receiver<mojom::DataDecoderService> receiver_{this};
+  // In-process instances (e.g. on iOS or in tests) may have multiple concurrent
+  // remote DataDecoderService clients.
+  mojo::ReceiverSet<mojom::DataDecoderService> receivers_;
 
   bool drop_image_decoders_ = false;
   bool drop_json_parsers_ = false;