Add Static Initializer for leak detector TLS

components/metrics/leak_detector/leak_detector.h

 // Copyright 2016 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 COMPONENTS_METRICS_LEAK_DETECTOR_LEAK_DETECTOR_H_
 #define COMPONENTS_METRICS_LEAK_DETECTOR_LEAK_DETECTOR_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <list>
 #include <memory>
 #include <vector>
 
 #include "base/feature_list.h"
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/observer_list.h"
 #include "base/synchronization/lock.h"
 #include "base/task_runner.h"
 #include "base/threading/thread_checker.h"
-#include "components/metrics/proto/memory_leak_report.pb.h"
 
 namespace base {
 template <typename T>
 struct DefaultLazyInstanceTraits;
 }
 
 namespace metrics {
 
+class MemoryLeakReportProto;
+class MemoryLeakReportProto_Params;
+
 namespace leak_detector {
 class LeakDetectorImpl;
 }
 
 // LeakDetector is an interface layer that connects the allocator
 // (base::allocator), the leak detector logic (LeakDetectorImpl), and any
 // external classes interested in receiving leak reports (extend the Observer
 // class).
 //
 // Only one instance of this class can exist. Access this instance using
@@ skipping 17 matching lines @@
     // Called by leak detector to report leaks.
     virtual void OnLeaksFound(
         const std::vector<MemoryLeakReportProto>& reports) = 0;
   };
 
   // Returns the sole instance, or creates it if it hasn't already been created.
   static LeakDetector* GetInstance();
 
   // Initializes leak detector. Args:
   // - |params| is a set of parameters used by the leak detector. See definition
-  //   of MemoryLeakReportProto::Params for info about individual parameters.
+  //   of MemoryLeakReportProto_Params for info about individual parameters.
   // - |task_runner| is a TaskRunner to which NotifyObservers() should be
   //   posted, if it is initally called from a different thread than the one on
   //   which |task_runner| runs.
-  void Init(const MemoryLeakReportProto::Params& params,
+  void Init(const MemoryLeakReportProto_Params& params,
             scoped_refptr<base::TaskRunner> task_runner);
 
+  // Initializes static elements within this class, such as TLS.
+  static void StaticInit();

[Primiano Tucci (use gerrit), 2016/06/01 21:26:30]

I'd call it InitTLSSlot() and not static init.
Technically static initializers are a different (and very evil) thing that we
forbid in chrome.
Here, yes, you are initializing a static thing, but that is not technically a
"static initializer" in the strict sense, as you are doing that in a proper
order and not depending on the loader.
It's just essentially a naming collision with something that you are not doing
:)

[Simon Que, 2016/06/02 17:55:17]

Done.

+
   // Add |observer| to the list of stored Observers, i.e. |observers_|, to which
   // the leak detector will report leaks.
   void AddObserver(Observer* observer);
 
   // Remove |observer| from |observers_|.
   void RemoveObserver(Observer* observer);
 
  private:
   friend base::DefaultLazyInstanceTraits<LeakDetector>;
   FRIEND_TEST_ALL_PREFIXES(LeakDetectorTest, NotifyObservers);
@@ skipping 61 matching lines @@
   // corresponds to the allowable range of |sampling_rate| passed in during
   // initialization: [0.0f, 1.0f] -> [0, UINT64_MAX].
   uint64_t sampling_factor_;
 
   DISALLOW_COPY_AND_ASSIGN(LeakDetector);
 };
 
 }  // namespace metrics
 
 #endif  // COMPONENTS_METRICS_LEAK_DETECTOR_LEAK_DETECTOR_H_