Move tracing_impl code to mojo/common

mojo/common/tracing_impl.h

+// Copyright 2014 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.
+
+#ifndef MOJO_COMMON_TRACING_IMPL_H_
+#define MOJO_COMMON_TRACING_IMPL_H_
+
+#include "base/basictypes.h"
+#include "base/files/file_path.h"
+#include "mojo/common/tracing.mojom.h"
+#include "mojo/public/cpp/bindings/strong_binding.h"
+
+namespace mojo {
+
+class TracingImpl : public Tracing {
+ public:
+  TracingImpl(InterfaceRequest<Tracing> request,
+              base::FilePath::StringType base_name);
+  virtual ~TracingImpl();
+
+ private:
+  // Overridden from Tracing:
+  void Start() override;
+  void Stop() override;
+
+  base::FilePath::StringType base_name_;
+  StrongBinding<Tracing> binding_;
+
+  DISALLOW_COPY_AND_ASSIGN(TracingImpl);
+};
+
+}  // namespace mojo
+
+#endif  // MOJO_COMMON_TRACING_IMPL_H_