Fix broken build on Win32 due to r11010.

src/platform-win32.cc

Index: src/platform-win32.cc
diff --git a/src/platform-win32.cc b/src/platform-win32.cc
index 72530b685a88226c01e8b98b44ce2f2efe5fabb2..98f04ea8c86c91abf9103df7be0e5c261efc5b65 100644
--- a/src/platform-win32.cc
+++ b/src/platform-win32.cc
@@ -1961,7 +1961,7 @@ class SamplerThread : public Thread {
         interval_(interval) {}
 
   static void AddActiveSampler(Sampler* sampler) {
-    ScopedLock lock(mutex_);
+    ScopedLock lock(mutex_.Pointer());
     SamplerRegistry::AddActiveSampler(sampler);
     if (instance_ == NULL) {
       instance_ = new SamplerThread(sampler->interval());
@@ -1972,7 +1972,7 @@ class SamplerThread : public Thread {
   }
 
   static void RemoveActiveSampler(Sampler* sampler) {
-    ScopedLock lock(mutex_);
+    ScopedLock lock(mutex_.Pointer());
     SamplerRegistry::RemoveActiveSampler(sampler);
     if (SamplerRegistry::GetState() == SamplerRegistry::HAS_NO_SAMPLERS) {
       RuntimeProfiler::StopRuntimeProfilerThreadBeforeShutdown(instance_);