Remove dependency on cc::TestNowSource from scheduler code

content/child/scheduler/time_source.h

+// 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.
+
+#ifndef CONTENT_CHILD_SCHEDULER_TIME_SOURCE_H_
+#define CONTENT_CHILD_SCHEDULER_TIME_SOURCE_H_
+
+#include "base/time/time.h"
+#include "content/common/content_export.h"
+
+namespace content {
+
+class CONTENT_EXPORT TimeSource {
+ public:
+  TimeSource();
+  virtual ~TimeSource();
+
+  virtual base::TimeTicks Now() const;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(TimeSource);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_CHILD_SCHEDULER_TIME_SOURCE_H_