Add Static Initializer for leak detector TLS

components/metrics/leak_detector/leak_detector.h

Index: components/metrics/leak_detector/leak_detector.h
diff --git a/components/metrics/leak_detector/leak_detector.h b/components/metrics/leak_detector/leak_detector.h
index fb624a281dd2eb59bdd951eb1a46634a5d4e73d7..0faf821c5e78f21f198dbc3a30af56578b4d76ca 100644
--- a/components/metrics/leak_detector/leak_detector.h
+++ b/components/metrics/leak_detector/leak_detector.h
@@ -20,7 +20,6 @@
 #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>
@@ -29,6 +28,9 @@ struct DefaultLazyInstanceTraits;
 
 namespace metrics {
 
+class MemoryLeakReportProto;
+class MemoryLeakReportProto_Params;
+
 namespace leak_detector {
 class LeakDetectorImpl;
 }
@@ -66,13 +68,16 @@ class LeakDetector {
 
   // 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);