[tracing] Add native allocation tracing mode.

base/trace_event/trace_event.h

Index: base/trace_event/trace_event.h
diff --git a/base/trace_event/trace_event.h b/base/trace_event/trace_event.h
index ef452f642f2ee7f419d0f213a77180a05accbc7d..68ae71ef946ba75d3d2175dcfd83def5f8b3be92 100644
--- a/base/trace_event/trace_event.h
+++ b/base/trace_event/trace_event.h
@@ -1056,17 +1056,21 @@ class ScopedTaskExecutionEvent {
  public:
   explicit ScopedTaskExecutionEvent(const char* task_context)
       : context_(task_context) {
+    using namespace base::trace_event;

[Primiano Tucci (use gerrit), 2016/04/21 20:08:21]

Just using base::trace_event::AllocationContextTracker;
using namespace is forbidden by our coding style.
("You may not use a using-directive to make all names from a namespace
available.")

same below

[Dmitry Skiba, 2016/04/22 06:31:15]

Done.

     if (UNLIKELY(
-            base::trace_event::AllocationContextTracker::capture_enabled())) {
-      base::trace_event::AllocationContextTracker::GetInstanceForCurrentThread()
+            AllocationContextTracker::capture_mode() !=
+            AllocationContextTracker::CaptureMode::DISABLED)) {
+      AllocationContextTracker::GetInstanceForCurrentThread()
           ->PushCurrentTaskContext(context_);
     }
   }
 
   ~ScopedTaskExecutionEvent() {
+    using namespace base::trace_event;
     if (UNLIKELY(
-            base::trace_event::AllocationContextTracker::capture_enabled())) {
-      base::trace_event::AllocationContextTracker::GetInstanceForCurrentThread()
+            AllocationContextTracker::capture_mode() !=
+            AllocationContextTracker::CaptureMode::DISABLED)) {
+      AllocationContextTracker::GetInstanceForCurrentThread()
           ->PopCurrentTaskContext(context_);
     }
   }