Separate WireClient.cpp into multiple files.

This patch copies methods and classes from WireClient.cpp and
distributes them over multiple files. Headers and forward declarations
are added as necessary, but no logical changes are made.

Bug: dawn:88
Change-Id: I9d0fcaeb67e789c3ad0597eaa3839adefc3ac5f9
Reviewed-on: https://dawn-review.googlesource.com/c/3980
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Austin Eng <enga@chromium.org>

src/dawn_wire/client/Client.cpp

@@ -0,0 +1,22 @@
+// Copyright 2019 The Dawn Authors
+//
+// 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
+//
+//     http://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.
+
+#include "dawn_wire/client/Client.h"
+
+namespace dawn_wire { namespace client {
+
+    Client::Client(Device* device) : mDevice(device) {
+    }
+
+}}  // namespace dawn_wire::client