Revert "Remove WEBRTC_TRACE."

This reverts commit 2209b90449473e1df3e0797b6271c7624b41907d.

Reason for revert: breaks Chromium

Original change's description:
> Remove WEBRTC_TRACE.
> 
> Bug: webrtc:5118
> Change-Id: I0af0f8845ee016fa61d7cecc526e2a672ec8732d
> Reviewed-on: https://webrtc-review.googlesource.com/5382
> Reviewed-by: Niels Moller <nisse@webrtc.org>
> Reviewed-by: Sami Kalliomäki <sakal@webrtc.org>
> Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
> Commit-Queue: Fredrik Solenberg <solenberg@webrtc.org>
> Cr-Commit-Position: refs/heads/master@{#20114}

TBR=solenberg@webrtc.org,sakal@webrtc.org,kwiberg@webrtc.org,nisse@webrtc.org

Change-Id: Ie54fc05c1d7895c088cba410ed87a7c9a0701427
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: webrtc:5118
Reviewed-on: https://webrtc-review.googlesource.com/5980
Reviewed-by: Fredrik Solenberg <solenberg@webrtc.org>
Commit-Queue: Fredrik Solenberg <solenberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#20115}
diff --git a/system_wrappers/source/trace_win.h b/system_wrappers/source/trace_win.h
new file mode 100644
index 0000000..b1a41f2
--- /dev/null
+++ b/system_wrappers/source/trace_win.h
@@ -0,0 +1,36 @@
+/*
+ *  Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef SYSTEM_WRAPPERS_SOURCE_TRACE_WIN_H_
+#define SYSTEM_WRAPPERS_SOURCE_TRACE_WIN_H_
+
+#include <stdio.h>
+#include <windows.h>
+
+#include "system_wrappers/source/trace_impl.h"
+
+namespace webrtc {
+
+class TraceWindows : public TraceImpl {
+ public:
+  TraceWindows();
+  virtual ~TraceWindows();
+
+  virtual int32_t AddTime(char* trace_message, const TraceLevel level) const;
+
+  virtual int32_t AddDateTimeInfo(char* trace_message) const;
+ private:
+  volatile mutable uint32_t prev_api_tick_count_;
+  volatile mutable uint32_t prev_tick_count_;
+};
+
+}  // namespace webrtc
+
+#endif  // SYSTEM_WRAPPERS_SOURCE_TRACE_WIN_H_