This CL is due the thread I have made on chromium-dev:...

base/condition_variable_unittest.cc

Index: base/condition_variable_unittest.cc
===================================================================
--- base/condition_variable_unittest.cc	(revision 3911)
+++ base/condition_variable_unittest.cc	(working copy)
@@ -14,6 +14,7 @@
 #include "base/platform_thread.h"
 #include "base/scoped_ptr.h"
 #include "base/spin_wait.h"
+#include "base/thread_collision_warner.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace {
@@ -76,6 +77,9 @@
   int shutdown_task_count() const;
 
   void thread_shutting_down();
+
+  //----------------------------------------------------------------------------
+  // Worker threads can call them but not needed to acquire a lock
   Lock* lock();
 
   ConditionVariable* work_is_available();
@@ -117,6 +121,8 @@
   TimeDelta worker_delay_;  // Time each task takes to complete.
   bool allow_help_requests_;  // Workers can signal more workers.
   bool shutdown_;  // Set when threads need to terminate.
+
+  D_DEFINE_CRITICAL_SECTION(locked_methods_);
 };
 
 //------------------------------------------------------------------------------
@@ -474,15 +480,18 @@
 }
 
 int WorkQueue::GetThreadId() {
+  D_SCOPED_RECURSIVE_BOOK_CRITICAL_SECTION(locked_methods_);
   DCHECK(!EveryIdWasAllocated());
   return thread_started_counter_++;  // Give out Unique IDs.
 }
 
 bool WorkQueue::EveryIdWasAllocated() const {
+  D_SCOPED_RECURSIVE_BOOK_CRITICAL_SECTION(locked_methods_);
   return thread_count_ == thread_started_counter_;
 }
 
 TimeDelta WorkQueue::GetAnAssignment(int thread_id) {
+  D_SCOPED_RECURSIVE_BOOK_CRITICAL_SECTION(locked_methods_);
   DCHECK_LT(0, task_count_);
   assignment_history_[thread_id]++;
   if (0 == --task_count_) {
@@ -492,26 +501,32 @@
 }
 
 void WorkQueue::WorkIsCompleted(int thread_id) {
+  D_SCOPED_RECURSIVE_BOOK_CRITICAL_SECTION(locked_methods_);
   completion_history_[thread_id]++;
 }
 
 int WorkQueue::task_count() const {
+  D_SCOPED_RECURSIVE_BOOK_CRITICAL_SECTION(locked_methods_);
   return task_count_;
 }
 
 bool WorkQueue::allow_help_requests() const {
+  D_SCOPED_RECURSIVE_BOOK_CRITICAL_SECTION(locked_methods_);
   return allow_help_requests_;
 }
 
 bool WorkQueue::shutdown() const {
+  D_SCOPED_RECURSIVE_BOOK_CRITICAL_SECTION(locked_methods_);
   return shutdown_;
 }
 
 int WorkQueue::shutdown_task_count() const {
+  D_SCOPED_RECURSIVE_BOOK_CRITICAL_SECTION(locked_methods_);
   return shutdown_task_count_;
 }
 
 void WorkQueue::thread_shutting_down() {
+  D_SCOPED_RECURSIVE_BOOK_CRITICAL_SECTION(locked_methods_);
   shutdown_task_count_++;
 }