Bug 891398 - don't use volatile in VisualEventTracer.cpp; r=mayhemer

DONTBUILD because NPOTB

xpcom/base/VisualEventTracer.cpp

@@ -25,12 +25,14 @@ const char kTypeChars[eventtracer::eLast] = {' ','N','S','W','E','D'};
 // Flushing thread and records queue monitor
 mozilla::Monitor * gMonitor = nullptr;
 
-// Accessed concurently but since this flag is not functionally critical
-// for optimization purposes is not accessed under a lock
-bool volatile gInitialized = false;
+// gInitialized and gCapture can be accessed from multiple threads
+// simultaneously without any locking.  However, since they are only ever
+// *set* from the main thread, the chance of races manifesting is small
+// and unlikely to be a problem in practice.
+bool gInitialized;
 
 // Flag to allow capturing
-bool volatile gCapture = false;
+bool gCapture;
 
 // Time stamp of the epoch we have started to capture
 mozilla::TimeStamp * gProfilerStart;
@@ -129,7 +131,7 @@ public:
 
   Record * mRecordsHead;
   Record * mRecordsTail;
-  Record * volatile mNextRecord;
+  Record * mNextRecord;
 
   RecordBatch * mNextBatch;
   char * mThreadNameCopy;
@@ -138,8 +140,8 @@ public:
 
 // Protected by gMonitor, accessed concurently
 // Linked list of batches threads want to flush on disk
-RecordBatch * volatile gLogHead = nullptr;
-RecordBatch * volatile gLogTail = nullptr;
+RecordBatch * gLogHead = nullptr;
+RecordBatch * gLogTail = nullptr;
 
 // Registers the batch in the linked list
 // static