Minimize uses of lazy initialization by adding explicit initialization functions.

src/log.cc

Index: src/log.cc
diff --git a/src/log.cc b/src/log.cc
index 21d64df21c7abb426964b2f50377143f705a6120..8e01476b90247f81f033cd7b81ccc1e86cf80f22 100644
--- a/src/log.cc
+++ b/src/log.cc
@@ -1730,13 +1730,20 @@ void Logger::EnableSlidingStateWindow() {
 }
 
 // Protects the state below.
-static LazyMutex active_samplers_mutex = LAZY_MUTEX_INITIALIZER;
+static Mutex* active_samplers_mutex = NULL;
 
 List<Sampler*>* SamplerRegistry::active_samplers_ = NULL;
 
 
+void SamplerRegistry::GlobalSetUp() {
+  if (!active_samplers_mutex) {
+    active_samplers_mutex = OS::CreateMutex();
+  }
+}
+
+
 bool SamplerRegistry::IterateActiveSamplers(VisitSampler func, void* param) {
-  ScopedLock lock(active_samplers_mutex.Pointer());
+  ScopedLock lock(active_samplers_mutex);
   for (int i = 0;
        ActiveSamplersExist() && i < active_samplers_->length();
        ++i) {
@@ -1763,7 +1770,7 @@ SamplerRegistry::State SamplerRegistry::GetState() {
 
 void SamplerRegistry::AddActiveSampler(Sampler* sampler) {
   ASSERT(sampler->IsActive());
-  ScopedLock lock(active_samplers_mutex.Pointer());
+  ScopedLock lock(active_samplers_mutex);
   if (active_samplers_ == NULL) {
     active_samplers_ = new List<Sampler*>;
   } else {
@@ -1775,7 +1782,7 @@ void SamplerRegistry::AddActiveSampler(Sampler* sampler) {
 
 void SamplerRegistry::RemoveActiveSampler(Sampler* sampler) {
   ASSERT(sampler->IsActive());
-  ScopedLock lock(active_samplers_mutex.Pointer());
+  ScopedLock lock(active_samplers_mutex);
   ASSERT(active_samplers_ != NULL);
   bool removed = active_samplers_->RemoveElement(sampler);
   ASSERT(removed);