Expose global state variables for sampling tracing to WebKit

webkit/glue/webkitplatformsupport_impl.h

Index: webkit/glue/webkitplatformsupport_impl.h
diff --git a/webkit/glue/webkitplatformsupport_impl.h b/webkit/glue/webkitplatformsupport_impl.h
index 859309e5735dca8b1b3eab0c5706fc1b572d9052..0f77447f5714e54ebaf11a629fddbff841509446 100644
--- a/webkit/glue/webkitplatformsupport_impl.h
+++ b/webkit/glue/webkitplatformsupport_impl.h
@@ -6,6 +6,7 @@
 #define WEBKIT_PLATFORM_SUPPORT_IMPL_H_
 
 #include "base/compiler_specific.h"
+#include "base/debug/trace_event.h"
 #include "base/platform_file.h"
 #include "base/threading/thread_local_storage.h"
 #include "base/timer.h"
@@ -88,6 +89,7 @@ class WEBKIT_GLUE_EXPORT WebKitPlatformSupportImpl :
     const char* name, int sample, int boundary_value);
   virtual const unsigned char* getTraceCategoryEnabledFlag(
       const char* category_name);
+  virtual long* getTraceSamplingState(const unsigned thread_bucket);
   virtual void addTraceEvent(
       char phase,
       const unsigned char* category_enabled,