Revert of Move tracing namespace from base::debug to base::trace_event. (patchset #7 id:120001 of https://codereview.chromium.org/882673002/)

Reason for revert:
broken Memory.FYI TSan bot.
crbug.com/455530

Original issue's description:
> Move tracing namespace from base::debug to base::trace_event.
>
> After having transitioned all the tracing headers from base/debug/ to
> base/trace_event, this CL addresses the namespace move.
> In principle, this CL should only change the namespace of the
> base/trace_event files but the namespace used by the tracing clients.
> In order to achieve this, namespace aliases are appended to the
> trace_event headers, to make it so that clients can still refer to
> base::debug::TraceFoo, with that being aliased to
> base::trace_event::TraceFoo.
> The upcoming CLs will gradually migrate the clients to use the
> base::trace_event namespace and will remove the ns aliases.
> Unfortunately, this CL has also to update few tracing clients,
> in particular the ones having forward declarations. Forward
> declarations, in fact, cannot be aliased as the compiler sees them
> before the alias itself.
>
> See crrev.com/837303004 and the related bug for motivations and design doc.
>
> BUG=451032
> TBR=skyostil@chromium.org,jam@chromium.org
>
> Committed: https://crrev.com/97c5abba36f5ce473cd996fab74fbf5aa9bb5464
> Cr-Commit-Position: refs/heads/master@{#314657}

TBR=dsinclair@chromium.org,picksi@chromium.org,primiano@chromium.org,skyostil@chromium.org,ssid@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=451032

Review URL: https://codereview.chromium.org/904573002

Cr-Commit-Position: refs/heads/master@{#314740}

21 files changed, 105 insertions, 161 deletions

diff --git a/base/trace_event/trace_event.h b/base/trace_event/trace_event.h
index a4c4f83..7f73071 100644
--- a/base/trace_event/trace_event.h
+++ b/base/trace_event/trace_event.h
@@ -141,7 +141,7 @@
 // means, if the category for the event is disabled, the conversion will not
 // happen.
 //
-//   class MyData : public base::trace_event::ConvertableToTraceFormat {
+//   class MyData : public base::debug::ConvertableToTraceFormat {
 //    public:
 //     MyData() {}
 //     virtual void AppendAsTraceFormat(std::string* out) const override {
@@ -795,8 +795,8 @@
 
 #define INTERNAL_TRACE_EVENT_CATEGORY_GROUP_ENABLED_FOR_RECORDING_MODE() \
     UNLIKELY(*INTERNAL_TRACE_EVENT_UID(category_group_enabled) & \
-        (base::trace_event::TraceLog::ENABLED_FOR_RECORDING | \
-         base::trace_event::TraceLog::ENABLED_FOR_EVENT_CALLBACK))
+        (base::debug::TraceLog::ENABLED_FOR_RECORDING | \
+         base::debug::TraceLog::ENABLED_FOR_EVENT_CALLBACK))
 
 // Macro to efficiently determine if a given category group is enabled.
 #define TRACE_EVENT_CATEGORY_GROUP_ENABLED(category_group, ret) \
@@ -839,16 +839,16 @@
 // const unsigned char*
 //     TRACE_EVENT_API_GET_CATEGORY_GROUP_ENABLED(const char* category_group)
 #define TRACE_EVENT_API_GET_CATEGORY_GROUP_ENABLED \
-    base::trace_event::TraceLog::GetCategoryGroupEnabled
+    base::debug::TraceLog::GetCategoryGroupEnabled
 
 // Get the number of times traces have been recorded. This is used to implement
 // the TRACE_EVENT_IS_NEW_TRACE facility.
 // unsigned int TRACE_EVENT_API_GET_NUM_TRACES_RECORDED()
 #define TRACE_EVENT_API_GET_NUM_TRACES_RECORDED \
-    base::trace_event::TraceLog::GetInstance()->GetNumTracesRecorded
+    base::debug::TraceLog::GetInstance()->GetNumTracesRecorded
 
 // Add a trace event to the platform tracing system.
-// base::trace_event::TraceEventHandle TRACE_EVENT_API_ADD_TRACE_EVENT(
+// base::debug::TraceEventHandle TRACE_EVENT_API_ADD_TRACE_EVENT(
 //                    char phase,
 //                    const unsigned char* category_group_enabled,
 //                    const char* name,
@@ -859,11 +859,10 @@
 //                    const unsigned long long* arg_values,
 //                    unsigned char flags)
 #define TRACE_EVENT_API_ADD_TRACE_EVENT \
-    base::trace_event::TraceLog::GetInstance()->AddTraceEvent
+    base::debug::TraceLog::GetInstance()->AddTraceEvent
 
 // Add a trace event to the platform tracing system.
-// base::trace_event::TraceEventHandle
-// TRACE_EVENT_API_ADD_TRACE_EVENT_WITH_TIMESTAMP(
+// base::debug::TraceEventHandle TRACE_EVENT_API_ADD_TRACE_EVENT_WITH_TIMESTAMP(
 //                    char phase,
 //                    const unsigned char* category_group_enabled,
 //                    const char* name,
@@ -876,16 +875,15 @@
 //                    const unsigned long long* arg_values,
 //                    unsigned char flags)
 #define TRACE_EVENT_API_ADD_TRACE_EVENT_WITH_THREAD_ID_AND_TIMESTAMP \
-    base::trace_event::TraceLog::GetInstance() \
-      ->AddTraceEventWithThreadIdAndTimestamp
+    base::debug::TraceLog::GetInstance()->AddTraceEventWithThreadIdAndTimestamp
 
 // Set the duration field of a COMPLETE trace event.
 // void TRACE_EVENT_API_UPDATE_TRACE_EVENT_DURATION(
 //     const unsigned char* category_group_enabled,
 //     const char* name,
-//     base::trace_event::TraceEventHandle id)
+//     base::debug::TraceEventHandle id)
 #define TRACE_EVENT_API_UPDATE_TRACE_EVENT_DURATION \
-    base::trace_event::TraceLog::GetInstance()->UpdateTraceEventDuration
+    base::debug::TraceLog::GetInstance()->UpdateTraceEventDuration
 
 // Defines atomic operations used internally by the tracing system.
 #define TRACE_EVENT_API_ATOMIC_WORD base::subtle::AtomicWord
@@ -958,12 +956,11 @@ TRACE_EVENT_API_CLASS_EXPORT extern \
     INTERNAL_TRACE_EVENT_GET_CATEGORY_INFO(category_group); \
     trace_event_internal::ScopedTracer INTERNAL_TRACE_EVENT_UID(tracer); \
     if (INTERNAL_TRACE_EVENT_CATEGORY_GROUP_ENABLED_FOR_RECORDING_MODE()) { \
-      base::trace_event::TraceEventHandle h = \
-          trace_event_internal::AddTraceEvent( \
-              TRACE_EVENT_PHASE_COMPLETE, \
-              INTERNAL_TRACE_EVENT_UID(category_group_enabled), name, \
-              trace_event_internal::kNoEventId, TRACE_EVENT_FLAG_NONE, \
-              ##__VA_ARGS__); \
+      base::debug::TraceEventHandle h = trace_event_internal::AddTraceEvent( \
+          TRACE_EVENT_PHASE_COMPLETE, \
+          INTERNAL_TRACE_EVENT_UID(category_group_enabled), \
+          name, trace_event_internal::kNoEventId, \
+          TRACE_EVENT_FLAG_NONE, ##__VA_ARGS__); \
       INTERNAL_TRACE_EVENT_UID(tracer).Initialize( \
           INTERNAL_TRACE_EVENT_UID(category_group_enabled), name, h); \
     }
@@ -1256,7 +1253,7 @@ static inline void SetTraceValue(const base::TimeTicks arg,
 // pointers to the internal c_str and pass through to the tracing API,
 // the arg_values must live throughout these procedures.
 
-static inline base::trace_event::TraceEventHandle
+static inline base::debug::TraceEventHandle
 AddTraceEventWithThreadIdAndTimestamp(
     char phase,
     const unsigned char* category_group_enabled,
@@ -1266,8 +1263,7 @@ AddTraceEventWithThreadIdAndTimestamp(
     const base::TimeTicks& timestamp,
     unsigned char flags,
     const char* arg1_name,
-    const scoped_refptr<base::trace_event::ConvertableToTraceFormat>&
-        arg1_val) {
+    const scoped_refptr<base::debug::ConvertableToTraceFormat>& arg1_val) {
   const int num_args = 1;
   unsigned char arg_types[1] = { TRACE_VALUE_TYPE_CONVERTABLE };
   return TRACE_EVENT_API_ADD_TRACE_EVENT_WITH_THREAD_ID_AND_TIMESTAMP(
@@ -1276,7 +1272,7 @@ AddTraceEventWithThreadIdAndTimestamp(
 }
 
 template<class ARG1_TYPE>
-static inline base::trace_event::TraceEventHandle
+static inline base::debug::TraceEventHandle
 AddTraceEventWithThreadIdAndTimestamp(
     char phase,
     const unsigned char* category_group_enabled,
@@ -1288,8 +1284,7 @@ AddTraceEventWithThreadIdAndTimestamp(
     const char* arg1_name,
     const ARG1_TYPE& arg1_val,
     const char* arg2_name,
-    const scoped_refptr<base::trace_event::ConvertableToTraceFormat>&
-        arg2_val) {
+    const scoped_refptr<base::debug::ConvertableToTraceFormat>& arg2_val) {
   const int num_args = 2;
   const char* arg_names[2] = { arg1_name, arg2_name };
 
@@ -1298,8 +1293,7 @@ AddTraceEventWithThreadIdAndTimestamp(
   SetTraceValue(arg1_val, &arg_types[0], &arg_values[0]);
   arg_types[1] = TRACE_VALUE_TYPE_CONVERTABLE;
 
-  scoped_refptr<base::trace_event::ConvertableToTraceFormat>
-      convertable_values[2];
+  scoped_refptr<base::debug::ConvertableToTraceFormat> convertable_values[2];
   convertable_values[1] = arg2_val;
 
   return TRACE_EVENT_API_ADD_TRACE_EVENT_WITH_THREAD_ID_AND_TIMESTAMP(
@@ -1308,7 +1302,7 @@ AddTraceEventWithThreadIdAndTimestamp(
 }
 
 template<class ARG2_TYPE>
-static inline base::trace_event::TraceEventHandle
+static inline base::debug::TraceEventHandle
 AddTraceEventWithThreadIdAndTimestamp(
     char phase,
     const unsigned char* category_group_enabled,
@@ -1318,7 +1312,7 @@ AddTraceEventWithThreadIdAndTimestamp(
     const base::TimeTicks& timestamp,
     unsigned char flags,
     const char* arg1_name,
-    const scoped_refptr<base::trace_event::ConvertableToTraceFormat>& arg1_val,
+    const scoped_refptr<base::debug::ConvertableToTraceFormat>& arg1_val,
     const char* arg2_name,
     const ARG2_TYPE& arg2_val) {
   const int num_args = 2;
@@ -1330,8 +1324,7 @@ AddTraceEventWithThreadIdAndTimestamp(
   arg_values[0] = 0;
   SetTraceValue(arg2_val, &arg_types[1], &arg_values[1]);
 
-  scoped_refptr<base::trace_event::ConvertableToTraceFormat>
-      convertable_values[2];
+  scoped_refptr<base::debug::ConvertableToTraceFormat> convertable_values[2];
   convertable_values[0] = arg1_val;
 
   return TRACE_EVENT_API_ADD_TRACE_EVENT_WITH_THREAD_ID_AND_TIMESTAMP(
@@ -1339,7 +1332,7 @@ AddTraceEventWithThreadIdAndTimestamp(
       num_args, arg_names, arg_types, arg_values, convertable_values, flags);
 }
 
-static inline base::trace_event::TraceEventHandle
+static inline base::debug::TraceEventHandle
 AddTraceEventWithThreadIdAndTimestamp(
     char phase,
     const unsigned char* category_group_enabled,
@@ -1349,23 +1342,22 @@ AddTraceEventWithThreadIdAndTimestamp(
     const base::TimeTicks& timestamp,
     unsigned char flags,
     const char* arg1_name,
-    const scoped_refptr<base::trace_event::ConvertableToTraceFormat>& arg1_val,
+    const scoped_refptr<base::debug::ConvertableToTraceFormat>& arg1_val,
     const char* arg2_name,
-    const scoped_refptr<base::trace_event::ConvertableToTraceFormat>&
-        arg2_val) {
+    const scoped_refptr<base::debug::ConvertableToTraceFormat>& arg2_val) {
   const int num_args = 2;
   const char* arg_names[2] = { arg1_name, arg2_name };
   unsigned char arg_types[2] =
       { TRACE_VALUE_TYPE_CONVERTABLE, TRACE_VALUE_TYPE_CONVERTABLE };
-  scoped_refptr<base::trace_event::ConvertableToTraceFormat>
-      convertable_values[2] = {arg1_val, arg2_val};
+  scoped_refptr<base::debug::ConvertableToTraceFormat> convertable_values[2] =
+      { arg1_val, arg2_val };
 
   return TRACE_EVENT_API_ADD_TRACE_EVENT_WITH_THREAD_ID_AND_TIMESTAMP(
       phase, category_group_enabled, name, id, thread_id, timestamp,
       num_args, arg_names, arg_types, NULL, convertable_values, flags);
 }
 
-static inline base::trace_event::TraceEventHandle
+static inline base::debug::TraceEventHandle
 AddTraceEventWithThreadIdAndTimestamp(
     char phase,
     const unsigned char* category_group_enabled,
@@ -1379,7 +1371,7 @@ AddTraceEventWithThreadIdAndTimestamp(
       kZeroNumArgs, NULL, NULL, NULL, NULL, flags);
 }
 
-static inline base::trace_event::TraceEventHandle AddTraceEvent(
+static inline base::debug::TraceEventHandle AddTraceEvent(
     char phase,
     const unsigned char* category_group_enabled,
     const char* name,
@@ -1392,7 +1384,7 @@ static inline base::trace_event::TraceEventHandle AddTraceEvent(
 }
 
 template<class ARG1_TYPE>
-static inline base::trace_event::TraceEventHandle
+static inline base::debug::TraceEventHandle
 AddTraceEventWithThreadIdAndTimestamp(
     char phase,
     const unsigned char* category_group_enabled,
@@ -1413,7 +1405,7 @@ AddTraceEventWithThreadIdAndTimestamp(
 }
 
 template<class ARG1_TYPE>
-static inline base::trace_event::TraceEventHandle AddTraceEvent(
+static inline base::debug::TraceEventHandle AddTraceEvent(
     char phase,
     const unsigned char* category_group_enabled,
     const char* name,
@@ -1429,7 +1421,7 @@ static inline base::trace_event::TraceEventHandle AddTraceEvent(
 }
 
 template<class ARG1_TYPE, class ARG2_TYPE>
-static inline base::trace_event::TraceEventHandle
+static inline base::debug::TraceEventHandle
 AddTraceEventWithThreadIdAndTimestamp(
     char phase,
     const unsigned char* category_group_enabled,
@@ -1454,7 +1446,7 @@ AddTraceEventWithThreadIdAndTimestamp(
 }
 
 template<class ARG1_TYPE, class ARG2_TYPE>
-static inline base::trace_event::TraceEventHandle AddTraceEvent(
+static inline base::debug::TraceEventHandle AddTraceEvent(
     char phase,
     const unsigned char* category_group_enabled,
     const char* name,
@@ -1486,7 +1478,7 @@ class TRACE_EVENT_API_CLASS_EXPORT ScopedTracer {
 
   void Initialize(const unsigned char* category_group_enabled,
                   const char* name,
-                  base::trace_event::TraceEventHandle event_handle) {
+                  base::debug::TraceEventHandle event_handle) {
     data_.category_group_enabled = category_group_enabled;
     data_.name = name;
     data_.event_handle = event_handle;
@@ -1502,7 +1494,7 @@ class TRACE_EVENT_API_CLASS_EXPORT ScopedTracer {
   struct Data {
     const unsigned char* category_group_enabled;
     const char* name;
-    base::trace_event::TraceEventHandle event_handle;
+    base::debug::TraceEventHandle event_handle;
   };
   Data* p_data_;
   Data data_;
@@ -1517,7 +1509,7 @@ class TRACE_EVENT_API_CLASS_EXPORT ScopedTraceBinaryEfficient {
  private:
   const unsigned char* category_group_enabled_;
   const char* name_;
-  base::trace_event::TraceEventHandle event_handle_;
+  base::debug::TraceEventHandle event_handle_;
 };
 
 // This macro generates less code then TRACE_EVENT0 but is also
@@ -1563,7 +1555,7 @@ class TraceEventSamplingStateScope {
 }  // namespace trace_event_internal
 
 namespace base {
-namespace trace_event {
+namespace debug {
 
 template<typename IDType> class TraceScopedTrackableObject {
  public:
@@ -1591,15 +1583,7 @@ template<typename IDType> class TraceScopedTrackableObject {
   DISALLOW_COPY_AND_ASSIGN(TraceScopedTrackableObject);
 };
 
-}  // 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::TraceScopedTrackableObject;
-}  // namespace debug
-}  // namespace base
+} // namespace debug
+} // namespace base
 
 #endif /* BASE_TRACE_EVENT_TRACE_EVENT_H_ */
diff --git a/base/trace_event/trace_event_android.cc b/base/trace_event/trace_event_android.cc
index bcba436..31da26d 100644
--- a/base/trace_event/trace_event_android.cc
+++ b/base/trace_event/trace_event_android.cc
@@ -24,8 +24,8 @@ void WriteEvent(
     unsigned long long id,
     const char** arg_names,
     const unsigned char* arg_types,
-    const base::trace_event::TraceEvent::TraceValue* arg_values,
-    const scoped_refptr<base::trace_event::ConvertableToTraceFormat>*
+    const base::debug::TraceEvent::TraceValue* arg_values,
+    const scoped_refptr<base::debug::ConvertableToTraceFormat>*
         convertable_values,
     unsigned char flags) {
   std::string out = base::StringPrintf("%c|%d|%s", phase, getpid(), name);
@@ -33,8 +33,7 @@ void WriteEvent(
     base::StringAppendF(&out, "-%" PRIx64, static_cast<uint64>(id));
   out += '|';
 
-  for (int i = 0; i < base::trace_event::kTraceMaxNumArgs && arg_names[i];
-       ++i) {
+  for (int i = 0; i < base::debug::kTraceMaxNumArgs && arg_names[i]; ++i) {
     if (i)
       out += ';';
     out += arg_names[i];
@@ -43,8 +42,8 @@ void WriteEvent(
     if (arg_types[i] == TRACE_VALUE_TYPE_CONVERTABLE) {
       convertable_values[i]->AppendAsTraceFormat(&out);
     } else {
-      base::trace_event::TraceEvent::AppendValueAsJSON(arg_types[i],
-                                                       arg_values[i], &out);
+      base::debug::TraceEvent::AppendValueAsJSON(
+          arg_types[i], arg_values[i], &out);
     }
     // Remove the quotes which may confuse the atrace script.
     ReplaceSubstringsAfterOffset(&out, value_start, "\\\"", "'");
@@ -66,7 +65,7 @@ void NoOpOutputCallback(base::WaitableEvent* complete_event,
     complete_event->Signal();
 }
 
-void EndChromeTracing(base::trace_event::TraceLog* trace_log,
+void EndChromeTracing(base::debug::TraceLog* trace_log,
                       base::WaitableEvent* complete_event) {
   trace_log->SetDisabled();
   // Delete the buffered trace events as they have been sent to atrace.
@@ -76,7 +75,7 @@ void EndChromeTracing(base::trace_event::TraceLog* trace_log,
 }  // namespace
 
 namespace base {
-namespace trace_event {
+namespace debug {
 
 // These functions support Android systrace.py when 'webview' category is
 // traced. With the new adb_profile_chrome, we may have two phases:
@@ -196,5 +195,5 @@ void TraceLog::AddClockSyncMetadataEvent() {
   close(atrace_fd);
 }
 
-}  // namespace trace_event
+}  // namespace debug
 }  // namespace base
diff --git a/base/trace_event/trace_event_argument.cc b/base/trace_event/trace_event_argument.cc
index 91ed9e8..00fcde1 100644
--- a/base/trace_event/trace_event_argument.cc
+++ b/base/trace_event/trace_event_argument.cc
@@ -8,7 +8,7 @@
 #include "base/values.h"
 
 namespace base {
-namespace trace_event {
+namespace debug {
 
 TracedValue::TracedValue() : root_(new DictionaryValue()) {
   stack_.push_back(root_.get());
@@ -113,5 +113,5 @@ void TracedValue::AppendAsTraceFormat(std::string* out) const {
   DCHECK_EQ(1u, stack_.size()) << tmp;
 }
 
-}  // namespace trace_event
+}  // namespace debug
 }  // namespace base
diff --git a/base/trace_event/trace_event_argument.h b/base/trace_event/trace_event_argument.h
index 43a0f38..08a5b50 100644
--- a/base/trace_event/trace_event_argument.h
+++ b/base/trace_event/trace_event_argument.h
@@ -16,7 +16,7 @@ class DictionaryValue;
 class ListValue;
 class Value;
 
-namespace trace_event {
+namespace debug {
 
 class BASE_EXPORT TracedValue : public ConvertableToTraceFormat {
  public:
@@ -53,14 +53,6 @@ class BASE_EXPORT TracedValue : public ConvertableToTraceFormat {
   DISALLOW_COPY_AND_ASSIGN(TracedValue);
 };
 
-}  // 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::TracedValue;
 }  // namespace debug
 }  // namespace base
 
diff --git a/base/trace_event/trace_event_argument_unittest.cc b/base/trace_event/trace_event_argument_unittest.cc
index c59910e..39cafef 100644
--- a/base/trace_event/trace_event_argument_unittest.cc
+++ b/base/trace_event/trace_event_argument_unittest.cc
@@ -6,7 +6,7 @@
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace base {
-namespace trace_event {
+namespace debug {
 
 TEST(TraceEventArgumentTest, FlatDictionary) {
   scoped_refptr<TracedValue> value = new TracedValue();
@@ -49,5 +49,5 @@ TEST(TraceEventArgumentTest, Hierarchy) {
       json);
 }
 
-}  // namespace trace_event
+}  // namespace debug
 }  // namespace base
diff --git a/base/trace_event/trace_event_impl.cc b/base/trace_event/trace_event_impl.cc
index 95cf06d..a8a0cc1 100644
--- a/base/trace_event/trace_event_impl.cc
+++ b/base/trace_event/trace_event_impl.cc
@@ -41,8 +41,8 @@
 class DeleteTraceLogForTesting {
  public:
   static void Delete() {
-    Singleton<base::trace_event::TraceLog,
-              LeakySingletonTraits<base::trace_event::TraceLog>>::OnExit(0);
+    Singleton<base::debug::TraceLog,
+              LeakySingletonTraits<base::debug::TraceLog> >::OnExit(0);
   }
 };
 
@@ -50,7 +50,7 @@ class DeleteTraceLogForTesting {
 BASE_EXPORT TRACE_EVENT_API_ATOMIC_WORD g_trace_state[3];
 
 namespace base {
-namespace trace_event {
+namespace debug {
 
 namespace {
 
@@ -2560,7 +2560,7 @@ const CategoryFilter::StringList&
   return delays_;
 }
 
-}  // namespace trace_event
+}  // namespace debug
 }  // namespace base
 
 namespace trace_event_internal {
diff --git a/base/trace_event/trace_event_impl.h b/base/trace_event/trace_event_impl.h
index 742f6b6..6d04c76 100644
--- a/base/trace_event/trace_event_impl.h
+++ b/base/trace_event/trace_event_impl.h
@@ -27,17 +27,17 @@
 // Older style trace macros with explicit id and extra data
 // Only these macros result in publishing data to ETW as currently implemented.
 #define TRACE_EVENT_BEGIN_ETW(name, id, extra) \
-    base::trace_event::TraceLog::AddTraceEventEtw( \
+    base::debug::TraceLog::AddTraceEventEtw( \
         TRACE_EVENT_PHASE_BEGIN, \
         name, reinterpret_cast<const void*>(id), extra)
 
 #define TRACE_EVENT_END_ETW(name, id, extra) \
-    base::trace_event::TraceLog::AddTraceEventEtw( \
+    base::debug::TraceLog::AddTraceEventEtw( \
         TRACE_EVENT_PHASE_END, \
         name, reinterpret_cast<const void*>(id), extra)
 
 #define TRACE_EVENT_INSTANT_ETW(name, id, extra) \
-    base::trace_event::TraceLog::AddTraceEventEtw( \
+    base::debug::TraceLog::AddTraceEventEtw( \
         TRACE_EVENT_PHASE_INSTANT, \
         name, reinterpret_cast<const void*>(id), extra)
 
@@ -49,7 +49,7 @@ namespace base {
 class WaitableEvent;
 class MessageLoop;
 
-namespace trace_event {
+namespace debug {
 
 // For any argument of type TRACE_VALUE_TYPE_CONVERTABLE the provided
 // class must implement this interface.
@@ -807,23 +807,6 @@ class BASE_EXPORT TraceLog {
   DISALLOW_COPY_AND_ASSIGN(TraceLog);
 };
 
-}  // 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::CategoryFilter;
-using base::trace_event::ConvertableToTraceFormat;
-using base::trace_event::RECORD_UNTIL_FULL;
-using base::trace_event::RECORD_CONTINUOUSLY;
-using base::trace_event::RECORD_AS_MUCH_AS_POSSIBLE;
-using base::trace_event::TraceEventHandle;
-using base::trace_event::TraceLog;
-using base::trace_event::TraceLogStatus;
-using base::trace_event::TraceOptions;
-using base::trace_event::TraceResultBuffer;
 }  // namespace debug
 }  // namespace base
 
diff --git a/base/trace_event/trace_event_impl_constants.cc b/base/trace_event/trace_event_impl_constants.cc
index ffeacff..c46cf49 100644
--- a/base/trace_event/trace_event_impl_constants.cc
+++ b/base/trace_event/trace_event_impl_constants.cc
@@ -5,7 +5,7 @@
 #include "base/trace_event/trace_event_impl.h"
 
 namespace base {
-namespace trace_event {
+namespace debug {
 
 // Enable everything but debug and test categories by default.
 const char CategoryFilter::kDefaultCategoryFilterString[] = "-*Debug,-*Test";
@@ -24,5 +24,5 @@ const TraceLog::InternalTraceOptions
 const TraceLog::InternalTraceOptions
     TraceLog::kInternalRecordAsMuchAsPossible = 1 << 4;
 
-}  // namespace trace_event
+}  // namespace debug
 }  // namespace base
diff --git a/base/trace_event/trace_event_memory.cc b/base/trace_event/trace_event_memory.cc
index 2bf6d38..96b28e4 100644
--- a/base/trace_event/trace_event_memory.cc
+++ b/base/trace_event/trace_event_memory.cc
@@ -15,7 +15,7 @@
 #include "base/trace_event/trace_event.h"
 
 namespace base {
-namespace trace_event {
+namespace debug {
 
 namespace {
 
@@ -26,13 +26,13 @@ const size_t kMaxScopeDepth = 16;
 
 /////////////////////////////////////////////////////////////////////////////
 // Holds a memory dump until the tracing system needs to serialize it.
-class MemoryDumpHolder : public base::trace_event::ConvertableToTraceFormat {
+class MemoryDumpHolder : public base::debug::ConvertableToTraceFormat {
  public:
   // Takes ownership of dump, which must be a JSON string, allocated with
   // malloc() and NULL terminated.
   explicit MemoryDumpHolder(char* dump) : dump_(dump) {}
 
-  // base::trace_event::ConvertableToTraceFormat overrides:
+  // base::debug::ConvertableToTraceFormat overrides:
   void AppendAsTraceFormat(std::string* out) const override {
     AppendHeapProfileAsTraceFormat(dump_, out);
   }
@@ -165,7 +165,7 @@ TraceMemoryController::~TraceMemoryController() {
   TraceLog::GetInstance()->RemoveEnabledStateObserver(this);
 }
 
-// base::trace_event::TraceLog::EnabledStateChangedObserver overrides:
+  // base::debug::TraceLog::EnabledStateChangedObserver overrides:
 void TraceMemoryController::OnTraceLogEnabled() {
   // Check to see if tracing is enabled for the memory category.
   bool enabled;
@@ -436,5 +436,5 @@ const char* StringFromHexAddress(const std::string& hex_address) {
   return reinterpret_cast<const char*>(address);
 }
 
-}  // namespace trace_event
+}  // namespace debug
 }  // namespace base
diff --git a/base/trace_event/trace_event_memory.h b/base/trace_event/trace_event_memory.h
index 8e70020..f16467f 100644
--- a/base/trace_event/trace_event_memory.h
+++ b/base/trace_event/trace_event_memory.h
@@ -22,7 +22,7 @@ namespace base {
 
 class MessageLoopProxy;
 
-namespace trace_event {
+namespace debug {
 
 // Watches for chrome://tracing to be enabled or disabled. When tracing is
 // enabled, also enables tcmalloc heap profiling. This class is the preferred
@@ -46,7 +46,7 @@ class BASE_EXPORT TraceMemoryController
       GetHeapProfileFunction get_heap_profile_function);
   virtual ~TraceMemoryController();
 
-  // base::trace_event::TraceLog::EnabledStateChangedObserver overrides:
+  // base::debug::TraceLog::EnabledStateChangedObserver overrides:
   void OnTraceLogEnabled() override;
   void OnTraceLogDisabled() override;
 
@@ -146,7 +146,7 @@ BASE_EXPORT bool AppendHeapProfileLineAsTraceFormat(const std::string& line,
 // and "error" if |address| could not be parsed. Visible for testing.
 BASE_EXPORT const char* StringFromHexAddress(const std::string& hex_address);
 
-}  // namespace trace_event
+}  // namespace debug
 }  // namespace base
 
 // Make local variables with unique names based on the line number. Note that
@@ -159,7 +159,7 @@ BASE_EXPORT const char* StringFromHexAddress(const std::string& hex_address);
 // It generates a unique local variable name using the macros above.
 #if defined(TCMALLOC_TRACE_MEMORY_SUPPORTED)
 #define INTERNAL_TRACE_MEMORY(category, name) \
-  base::trace_event::ScopedTraceMemory INTERNAL_TRACE_MEMORY_ID(category, name);
+  base::debug::ScopedTraceMemory INTERNAL_TRACE_MEMORY_ID(category, name);
 #else
 #define INTERNAL_TRACE_MEMORY(category, name)
 #endif  // defined(TRACE_MEMORY_SUPPORTED)
diff --git a/base/trace_event/trace_event_memory_unittest.cc b/base/trace_event/trace_event_memory_unittest.cc
index 4732733..220c0e6 100644
--- a/base/trace_event/trace_event_memory_unittest.cc
+++ b/base/trace_event/trace_event_memory_unittest.cc
@@ -16,7 +16,7 @@
 #endif
 
 namespace base {
-namespace trace_event {
+namespace debug {
 
 // Tests for the trace event memory tracking system. Exists as a class so it
 // can be a friend of TraceMemoryController.
@@ -236,5 +236,5 @@ TEST_F(TraceMemoryTest, StringFromHexAddress) {
   EXPECT_STREQ(kHello, StringFromHexAddress(hex_address.str()));
 }
 
-}  // namespace trace_event
+}  // namespace debug
 }  // namespace base
diff --git a/base/trace_event/trace_event_synthetic_delay.cc b/base/trace_event/trace_event_synthetic_delay.cc
index 4b957c3..3651611 100644
--- a/base/trace_event/trace_event_synthetic_delay.cc
+++ b/base/trace_event/trace_event_synthetic_delay.cc
@@ -10,7 +10,7 @@ const int kMaxSyntheticDelays = 32;
 }  // namespace
 
 namespace base {
-namespace trace_event {
+namespace debug {
 
 TraceEventSyntheticDelayClock::TraceEventSyntheticDelayClock() {}
 TraceEventSyntheticDelayClock::~TraceEventSyntheticDelayClock() {}
@@ -200,7 +200,7 @@ void ResetTraceEventSyntheticDelays() {
   TraceEventSyntheticDelayRegistry::GetInstance()->ResetAllDelays();
 }
 
-}  // namespace trace_event
+}  // namespace debug
 }  // namespace base
 
 namespace trace_event_internal {
@@ -215,16 +215,15 @@ ScopedSyntheticDelay::~ScopedSyntheticDelay() {
   delay_impl_->EndParallel(end_time_);
 }
 
-base::trace_event::TraceEventSyntheticDelay* GetOrCreateDelay(
+base::debug::TraceEventSyntheticDelay* GetOrCreateDelay(
     const char* name,
     base::subtle::AtomicWord* impl_ptr) {
-  base::trace_event::TraceEventSyntheticDelay* delay_impl =
-      reinterpret_cast<base::trace_event::TraceEventSyntheticDelay*>(
+  base::debug::TraceEventSyntheticDelay* delay_impl =
+      reinterpret_cast<base::debug::TraceEventSyntheticDelay*>(
           base::subtle::Acquire_Load(impl_ptr));
   if (!delay_impl) {
-    delay_impl =
-        base::trace_event::TraceEventSyntheticDelayRegistry::GetInstance()
-            ->GetOrCreateDelay(name);
+    delay_impl = base::debug::TraceEventSyntheticDelayRegistry::GetInstance()
+                     ->GetOrCreateDelay(name);
     base::subtle::Release_Store(
         impl_ptr, reinterpret_cast<base::subtle::AtomicWord>(delay_impl));
   }
diff --git a/base/trace_event/trace_event_synthetic_delay.h b/base/trace_event/trace_event_synthetic_delay.h
index 14801be..b52f3b0 100644
--- a/base/trace_event/trace_event_synthetic_delay.h
+++ b/base/trace_event/trace_event_synthetic_delay.h
@@ -65,7 +65,7 @@ template <typename Type>
 struct DefaultSingletonTraits;
 
 namespace base {
-namespace trace_event {
+namespace debug {
 
 // Time source for computing delay durations. Used for testing.
 class TRACE_EVENT_API_CLASS_EXPORT TraceEventSyntheticDelayClock {
@@ -138,7 +138,7 @@ class TRACE_EVENT_API_CLASS_EXPORT TraceEventSyntheticDelay {
 // Set the target durations of all registered synthetic delay points to zero.
 TRACE_EVENT_API_CLASS_EXPORT void ResetTraceEventSyntheticDelays();
 
-}  // namespace trace_event
+}  // namespace debug
 }  // namespace base
 
 namespace trace_event_internal {
@@ -151,14 +151,14 @@ class TRACE_EVENT_API_CLASS_EXPORT ScopedSyntheticDelay {
   ~ScopedSyntheticDelay();
 
  private:
-  base::trace_event::TraceEventSyntheticDelay* delay_impl_;
+  base::debug::TraceEventSyntheticDelay* delay_impl_;
   base::TimeTicks end_time_;
 
   DISALLOW_COPY_AND_ASSIGN(ScopedSyntheticDelay);
 };
 
 // Helper for registering delays. Do not use directly.
-TRACE_EVENT_API_CLASS_EXPORT base::trace_event::TraceEventSyntheticDelay*
+TRACE_EVENT_API_CLASS_EXPORT base::debug::TraceEventSyntheticDelay*
     GetOrCreateDelay(const char* name, base::subtle::AtomicWord* impl_ptr);
 
 }  // namespace trace_event_internal
diff --git a/base/trace_event/trace_event_synthetic_delay_unittest.cc b/base/trace_event/trace_event_synthetic_delay_unittest.cc
index 1dc0fc2..84ac75c 100644
--- a/base/trace_event/trace_event_synthetic_delay_unittest.cc
+++ b/base/trace_event/trace_event_synthetic_delay_unittest.cc
@@ -7,7 +7,7 @@
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace base {
-namespace trace_event {
+namespace debug {
 namespace {
 
 const int kTargetDurationMs = 100;
@@ -150,5 +150,5 @@ TEST_F(TraceEventSyntheticDelayTest, BeginParallel) {
   EXPECT_LT((Now() - start_time).InMilliseconds(), kShortDurationMs);
 }
 
-}  // namespace trace_event
+}  // namespace debug
 }  // namespace base
diff --git a/base/trace_event/trace_event_system_stats_monitor.cc b/base/trace_event/trace_event_system_stats_monitor.cc
index 98f361a..6fa0174 100644
--- a/base/trace_event/trace_event_system_stats_monitor.cc
+++ b/base/trace_event/trace_event_system_stats_monitor.cc
@@ -16,13 +16,13 @@
 #include "base/trace_event/trace_event.h"
 
 namespace base {
-namespace trace_event {
+namespace debug {
 
 namespace {
 
 /////////////////////////////////////////////////////////////////////////////
 // Holds profiled system stats until the tracing system needs to serialize it.
-class SystemStatsHolder : public base::trace_event::ConvertableToTraceFormat {
+class SystemStatsHolder : public base::debug::ConvertableToTraceFormat {
  public:
   SystemStatsHolder() { }
 
@@ -30,7 +30,7 @@ class SystemStatsHolder : public base::trace_event::ConvertableToTraceFormat {
   // Uses the previous stats to compute rates if this is not the first profile.
   void GetSystemProfilingStats();
 
-  // base::trace_event::ConvertableToTraceFormat overrides:
+  // base::debug::ConvertableToTraceFormat overrides:
   void AppendAsTraceFormat(std::string* out) const override {
     AppendSystemProfileAsTraceFormat(system_stats_, out);
   }
@@ -129,5 +129,5 @@ void AppendSystemProfileAsTraceFormat(const SystemMetrics& system_metrics,
   *output += tmp;
 }
 
-}  // namespace trace_event
+}  // namespace debug
 }  // namespace base
diff --git a/base/trace_event/trace_event_system_stats_monitor.h b/base/trace_event/trace_event_system_stats_monitor.h
index 051669a..08fbfea 100644
--- a/base/trace_event/trace_event_system_stats_monitor.h
+++ b/base/trace_event/trace_event_system_stats_monitor.h
@@ -17,7 +17,7 @@ namespace base {
 
 class SingleThreadTaskRunner;
 
-namespace trace_event {
+namespace debug {
 
 // Watches for chrome://tracing to be enabled or disabled. When tracing is
 // enabled, also enables system events profiling. This class is the preferred
@@ -35,7 +35,7 @@ class BASE_EXPORT TraceEventSystemStatsMonitor
 
   virtual ~TraceEventSystemStatsMonitor();
 
-  // base::trace_event::TraceLog::EnabledStateChangedObserver overrides:
+  // base::debug::TraceLog::EnabledStateChangedObserver overrides:
   void OnTraceLogEnabled() override;
   void OnTraceLogDisabled() override;
 
@@ -69,7 +69,7 @@ BASE_EXPORT void AppendSystemProfileAsTraceFormat(const SystemMetrics&
                                                   system_stats,
                                                   std::string* output);
 
-}  // namespace trace_event
+}  // namespace debug
 }  // namespace base
 
 #endif  // BASE_TRACE_EVENT_TRACE_EVENT_SYSTEM_STATS_MONITOR_H_
diff --git a/base/trace_event/trace_event_system_stats_monitor_unittest.cc b/base/trace_event/trace_event_system_stats_monitor_unittest.cc
index 995f53b..143ac4a 100644
--- a/base/trace_event/trace_event_system_stats_monitor_unittest.cc
+++ b/base/trace_event/trace_event_system_stats_monitor_unittest.cc
@@ -12,7 +12,7 @@
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace base {
-namespace trace_event {
+namespace debug {
 
 #if !defined(OS_IOS)
 // Tests for the system stats monitor.
@@ -62,5 +62,5 @@ TEST_F(TraceSystemStatsMonitorTest, TraceEventSystemStatsMonitor) {
 }
 #endif  // !defined(OS_IOS)
 
-}  // namespace trace_event
+}  // namespace debug
 }  // namespace base
diff --git a/base/trace_event/trace_event_unittest.cc b/base/trace_event/trace_event_unittest.cc
index a6bc0d4..47b5ab6 100644
--- a/base/trace_event/trace_event_unittest.cc
+++ b/base/trace_event/trace_event_unittest.cc
@@ -25,7 +25,7 @@
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace base {
-namespace trace_event {
+namespace debug {
 
 namespace {
 
@@ -3079,5 +3079,6 @@ TEST(TraceOptionsTest, TraceOptionsToString) {
   }
 }
 
-}  // namespace trace_event
+
+}  // namespace debug
 }  // namespace base
diff --git a/base/trace_event/trace_event_win.cc b/base/trace_event/trace_event_win.cc
index ebb55c8..d2c3dc8 100644
--- a/base/trace_event/trace_event_win.cc
+++ b/base/trace_event/trace_event_win.cc
@@ -9,7 +9,7 @@
 #include <initguid.h>  // NOLINT
 
 namespace base {
-namespace trace_event {
+namespace debug {
 
 using base::win::EtwEventType;
 using base::win::EtwMofEvent;
@@ -120,5 +120,5 @@ void TraceEventETWProvider::Resurrect() {
   StaticMemorySingletonTraits<TraceEventETWProvider>::Resurrect();
 }
 
-}  // namespace trace_event
+}  // namespace debug
 }  // namespace base
diff --git a/base/trace_event/trace_event_win.h b/base/trace_event/trace_event_win.h
index dcb5aac..e447c35 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 trace_event {
+namespace debug {
 
 // This EtwTraceProvider subclass implements ETW logging
 // for the macros above on Windows.
@@ -119,20 +119,6 @@ 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
 
diff --git a/base/trace_event/trace_event_win_unittest.cc b/base/trace_event/trace_event_win_unittest.cc
index 7f1004e..a411301 100644
--- a/base/trace_event/trace_event_win_unittest.cc
+++ b/base/trace_event/trace_event_win_unittest.cc
@@ -20,7 +20,7 @@
 #include <initguid.h>  // NOLINT - must be last include.
 
 namespace base {
-namespace trace_event {
+namespace debug {
 
 namespace {
 
@@ -315,5 +315,5 @@ TEST_F(TraceEventWinTest, Macros) {
   PlayLog();
 }
 
-}  // namespace trace_event
+}  // namespace debug
 }  // namespace base