Add serializers for window.performance.

third_party/WebKit/Source/core/timing/MemoryInfo.h

Index: third_party/WebKit/Source/core/timing/MemoryInfo.h
diff --git a/third_party/WebKit/Source/core/timing/MemoryInfo.h b/third_party/WebKit/Source/core/timing/MemoryInfo.h
index 47cc91732f150c3ace6025fab11530150f65c58f..a38589b0bf4e083c18f8e17b366da5a9b459c2ee 100644
--- a/third_party/WebKit/Source/core/timing/MemoryInfo.h
+++ b/third_party/WebKit/Source/core/timing/MemoryInfo.h
@@ -38,6 +38,9 @@
 
 namespace blink {
 
+class ScriptState;
+class ScriptValue;
+
 struct HeapInfo {
   DISALLOW_NEW();
   HeapInfo() : usedJSHeapSize(0), totalJSHeapSize(0), jsHeapSizeLimit(0) {}
@@ -58,6 +61,8 @@ class CORE_EXPORT MemoryInfo final : public GarbageCollected<MemoryInfo>,
   size_t usedJSHeapSize() const { return m_info.usedJSHeapSize; }
   size_t jsHeapSizeLimit() const { return m_info.jsHeapSizeLimit; }
 
+  ScriptValue toJSONForBinding(ScriptState*) const;
+
   DEFINE_INLINE_TRACE() {}
 
  private: