Integrate network related part which both nearby sharing and fastpair are adopted.

Details can be seen in the `Integrate reusable internal components into third_party` part of `server access design doc` (go/fast_pair_server_data_access)

PiperOrigin-RevId: 498208011

internal/network/http_client_impl.h

@@ -0,0 +1,57 @@
+// Copyright 2022 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef THIRD_PARTY_NEARBY_INTERNAL_NETWORK_HTTP_CLIENT_IMPL_H_
+#define THIRD_PARTY_NEARBY_INTERNAL_NETWORK_HTTP_CLIENT_IMPL_H_
+
+#include <functional>
+#include <future> // NOLINT
+#include <thread> // NOLINT
+#include <utility>
+#include <vector>
+
+#include "absl/base/thread_annotations.h"
+#include "absl/synchronization/mutex.h"
+#include "internal/network/http_client.h"
+
+namespace location {
+namespace nearby {
+namespace network {
+
+class NearbyHttpClient : public HttpClient {
+ public:
+  NearbyHttpClient() = default;
+  ~NearbyHttpClient() override = default;
+
+  NearbyHttpClient(const NearbyHttpClient&) = default;
+  NearbyHttpClient& operator=(const NearbyHttpClient&) = default;
+  NearbyHttpClient(NearbyHttpClient&&) = default;
+  NearbyHttpClient& operator=(NearbyHttpClient&&) = default;
+
+  void StartRequest(const HttpRequest& request,
+                    std::function<void(const absl::StatusOr<HttpResponse>&)>
+                        callback) override ABSL_LOCKS_EXCLUDED(mutex_);
+
+ private:
+  void CleanThreads() ABSL_SHARED_LOCKS_REQUIRED(mutex_);
+
+  absl::Mutex mutex_;
+  std::vector<std::future<void>> http_threads_ ABSL_GUARDED_BY(mutex_);
+};
+
+}  // namespace network
+}  // namespace nearby
+}  // namespace location
+
+#endif  // THIRD_PARTY_NEARBY_INTERNAL_NETWORK_HTTP_CLIENT_IMPL_H_