Fix performance issue in InstanceCounters for DOM nodes

third_party/WebKit/Source/core/inspector/InstanceCounters.cpp

Index: third_party/WebKit/Source/core/inspector/InstanceCounters.cpp
diff --git a/third_party/WebKit/Source/core/inspector/InstanceCounters.cpp b/third_party/WebKit/Source/core/inspector/InstanceCounters.cpp
index c5948b98763ac088a1d4ea12c76fa93d1f63709a..50cf7181322887d85829936d53d96bcc4af3d7f8 100644
--- a/third_party/WebKit/Source/core/inspector/InstanceCounters.cpp
+++ b/third_party/WebKit/Source/core/inspector/InstanceCounters.cpp
@@ -34,7 +34,15 @@ namespace blink {
 
 int InstanceCounters::s_counters[CounterTypeLength];
 
+// Counts only nodes for a performance reason. Many node are created and atomic
+// barriers or locks should be avoided (crbug/641019).
+int InstanceCounters::s_nodeCounter;
+
 int InstanceCounters::counterValue(CounterType type) {
+  if (type == NodeCounter) {
+    DCHECK(isMainThread());
+    return s_nodeCounter;
+  }
   return acquireLoad(&s_counters[type]);
 }