Incorporate pwendell's code review suggestions.

core/src/main/scala/org/apache/spark/executor/Executor.scala

@@ -222,9 +222,9 @@ private[spark] class Executor(
           return
         }
 
-        val objectSer = SparkEnv.get.serializer.newInstance()
+        val resultSer = SparkEnv.get.serializer.newInstance()
         val beforeSerialization = System.currentTimeMillis()
-        val valueBytes = objectSer.serialize(value)
+        val valueBytes = resultSer.serialize(value)
         val afterSerialization = System.currentTimeMillis()
 
         for (m <- task.metrics) {
@@ -232,7 +232,7 @@ private[spark] class Executor(
           m.executorDeserializeTime = (taskStart - startTime).toInt
           m.executorRunTime = (taskFinish - taskStart).toInt
           m.jvmGCTime = gcTime - startGCTime
-          m.serializationTime = (afterSerialization - beforeSerialization).toInt
+          m.resultSerializationTime = (afterSerialization - beforeSerialization).toInt
         }
 
         val accumUpdates = Accumulators.values

core/src/main/scala/org/apache/spark/executor/TaskMetrics.scala

@@ -44,9 +44,9 @@ class TaskMetrics extends Serializable {
   var jvmGCTime: Long = _
 
   /**
-   * Amount of time spent serializing the result of the task
+   * Amount of time spent serializing the task result
    */
-  var serializationTime: Long = _
+  var resultSerializationTime: Long = _
 
   /**
    * If this task reads from shuffle output, metrics on getting shuffle data will be collected here

core/src/main/scala/org/apache/spark/ui/jobs/StagePage.scala

@@ -102,8 +102,8 @@ private[spark] class StagePage(parent: JobProgressUI) {
         }
         else {
           val serializationTimes = validTasks.map{case (info, metrics, exception) =>
-            metrics.get.serializationTime.toDouble}
-          val serializationQuantiles = "Serialization Time" +: Distribution(serializationTimes).get.getQuantiles().map(
+            metrics.get.resultSerializationTime.toDouble}
+          val serializationQuantiles = "Result serialization time" +: Distribution(serializationTimes).get.getQuantiles().map(
             ms => parent.formatDuration(ms.toLong))
 
           val serviceTimes = validTasks.map{case (info, metrics, exception) =>

core/src/test/scala/org/apache/spark/scheduler/cluster/ClusterTaskSetManagerSuite.scala

@@ -314,7 +314,6 @@ class ClusterTaskSetManagerSuite extends FunSuite with LocalSparkContext with Lo
 
   def createTaskResult(id: Int): DirectTaskResult[Int] = {
     val objectSer = SparkEnv.get.serializer.newInstance()
-    new DirectTaskResult[Int](objectSer.serialize(id), mutable.Map.empty,
-        new TaskMetrics)
+    new DirectTaskResult[Int](objectSer.serialize(id), mutable.Map.empty, new TaskMetrics)
   }
 }