Expose global state variables for sampling tracing to WebKit

webkit/glue/webkitplatformsupport_impl.cc

Index: webkit/glue/webkitplatformsupport_impl.cc
diff --git a/webkit/glue/webkitplatformsupport_impl.cc b/webkit/glue/webkitplatformsupport_impl.cc
index 34e63d231d2d0f34fecb63e44a0249bcd9ea41b6..0064ce93f12d8f0527ab298e9c69b622d8b5cdba 100644
--- a/webkit/glue/webkitplatformsupport_impl.cc
+++ b/webkit/glue/webkitplatformsupport_impl.cc
@@ -10,7 +10,6 @@
 
 #include "base/allocator/allocator_extension.h"
 #include "base/bind.h"
-#include "base/debug/trace_event.h"
 #include "base/memory/discardable_memory.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/singleton.h"
@@ -453,6 +452,21 @@ const unsigned char* WebKitPlatformSupportImpl::getTraceCategoryEnabledFlag(
   return TRACE_EVENT_API_GET_CATEGORY_ENABLED(category_name);
 }
 
+long* WebKitPlatformSupportImpl::getTraceSamplingState(
+    const unsigned thread_bucket) {
+  switch(thread_bucket) {
+  case 0:
+    return reinterpret_cast<long*>(&TRACE_EVENT_API_THREAD_BUCKET(0));
+  case 1:
+    return reinterpret_cast<long*>(&TRACE_EVENT_API_THREAD_BUCKET(1));
+  case 2:
+    return reinterpret_cast<long*>(&TRACE_EVENT_API_THREAD_BUCKET(2));
+  default:
+    NOTREACHED() << "Unknown thread bucket type.";
+  }
+  return NULL;
+}
+
 void WebKitPlatformSupportImpl::addTraceEvent(
     char phase,
     const unsigned char* category_enabled,