tracing: add dump provider for malloc heap profiler

base/trace_event/heap_profiler_allocation_context_tracker.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef BASE_TRACE_EVENT_HEAP_PROFILER_ALLOCATION_CONTEXT_TRACKER_H_
 #define BASE_TRACE_EVENT_HEAP_PROFILER_ALLOCATION_CONTEXT_TRACKER_H_
 
 #include <vector>
 
 #include "base/atomicops.h"
@@ skipping 25 matching lines @@
     if (subtle::NoBarrier_Load(&capture_enabled_) == 0)
       return false;
 
     // In the slow path, an acquire load is required to pair with the release
     // store in |SetCaptureEnabled|. This is to ensure that the TLS slot for
     // the thread-local allocation context tracker has been initialized if
     // |capture_enabled| returns true.
     return subtle::Acquire_Load(&capture_enabled_) != 0;
   }
 
+  // Returns the thread-local instance, creating one if necessary. Returns
+  // always a valid instance, unless it is called re-entrantly, in which case
+  // returns nullptr in the nested calls.
+  static AllocationContextTracker* GetInstanceForCurrentThread();
+
   // Pushes a frame onto the thread-local pseudo stack.
-  static void PushPseudoStackFrame(StackFrame frame);
+  void PushPseudoStackFrame(StackFrame frame);
 
   // Pops a frame from the thread-local pseudo stack.
-  static void PopPseudoStackFrame(StackFrame frame);
+  void PopPseudoStackFrame(StackFrame frame);
 
   // Returns a snapshot of the current thread-local context.
-  static AllocationContext GetContextSnapshot();
+  AllocationContext GetContextSnapshot();
 
   ~AllocationContextTracker();
 
  private:
   AllocationContextTracker();
 
-  static AllocationContextTracker* GetThreadLocalTracker();
-
   static subtle::Atomic32 capture_enabled_;
 
   // The pseudo stack where frames are |TRACE_EVENT| names.
   std::vector<StackFrame> pseudo_stack_;
 
   DISALLOW_COPY_AND_ASSIGN(AllocationContextTracker);
 };
 
 }  // namespace trace_event
 }  // namespace base
 
 #endif  // BASE_TRACE_EVENT_HEAP_PROFILER_ALLOCATION_CONTEXT_TRACKER_H_