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

base/trace_event/trace_event_memory_unittest.cc

Index: base/trace_event/trace_event_memory_unittest.cc
diff --git a/base/trace_event/trace_event_memory_unittest.cc b/base/trace_event/trace_event_memory_unittest.cc
index 220c0e6215a2a15ab8d57c68e31ea71508a8f23e..47327335ebac06cdc0b4abff566f51b817aea233 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 debug {
+namespace trace_event {
 
 // 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 debug
+}  // namespace trace_event
 }  // namespace base