Reland of Move tracing namespace from base::debug to base::trace_event.

base/trace_event/trace_event_win.h

Index: base/trace_event/trace_event_win.h
diff --git a/base/trace_event/trace_event_win.h b/base/trace_event/trace_event_win.h
index e447c35db8b2700f92690822d5516e912a4e4cba..dcb5aacc50b16fb3565cac90c51b3f4d669c6cb7 100644
--- a/base/trace_event/trace_event_win.h
+++ b/base/trace_event/trace_event_win.h
@@ -17,7 +17,7 @@ template <typename Type>
 struct StaticMemorySingletonTraits;
 
 namespace base {
-namespace debug {
+namespace trace_event {
 
 // This EtwTraceProvider subclass implements ETW logging
 // for the macros above on Windows.
@@ -119,6 +119,20 @@ enum TraceEventETWFlags {
 // Optionally the stack trace, consisting of a DWORD "depth", followed
 //    by an array of void* (machine bitness) of length "depth".
 
+}  // namespace trace_event
+}  // namespace base
+
+// TODO(ssid): remove these aliases after the tracing clients are moved to the
+// new trace_event namespace. See crbug.com/451032. ETA: March 2015.
+namespace base {
+namespace debug {
+using base::trace_event::kChromeTraceProviderName;
+using base::trace_event::kTraceEventClass32;
+using base::trace_event::kTraceEventClass64;
+using base::trace_event::kTraceEventTypeBegin;
+using base::trace_event::kTraceEventTypeEnd;
+using base::trace_event::kTraceEventTypeInstant;
+using base::trace_event::TraceEventETWProvider;
 }  // namespace debug
 }  // namespace base