Remove unwanted copyToVector() uses.

third_party/WebKit/Source/core/timing/PerformanceBase.cpp

Index: third_party/WebKit/Source/core/timing/PerformanceBase.cpp
diff --git a/third_party/WebKit/Source/core/timing/PerformanceBase.cpp b/third_party/WebKit/Source/core/timing/PerformanceBase.cpp
index 1c5fb3d84657a04bc2e19f2a783c6f78b93ea257..517acfe9e793aa08b8f2f81a4f4814dbbc55bb5e 100644
--- a/third_party/WebKit/Source/core/timing/PerformanceBase.cpp
+++ b/third_party/WebKit/Source/core/timing/PerformanceBase.cpp
@@ -410,14 +410,13 @@ void PerformanceBase::resumeSuspendedObservers()
 void PerformanceBase::deliverObservationsTimerFired(Timer<PerformanceBase>*)
 {
     ASSERT(isMainThread());
-    PerformanceObserverVector observers;
-    copyToVector(m_activeObservers, observers);
-    m_activeObservers.clear();
-    for (size_t i = 0; i < observers.size(); ++i) {
-        if (observers[i]->shouldBeSuspended())
-            m_suspendedObservers.add(observers[i]);
+    PerformanceObservers observers;
+    m_activeObservers.swap(observers);
+    for (const auto& observer : observers) {
+        if (observer->shouldBeSuspended())
+            m_suspendedObservers.add(observer);
         else
-            observers[i]->deliver();
+            observer->deliver();
     }
 }