dmprof: Bug fix: The label 'Timestamp' should be on the horizontal axis

BUG=None
NOTRY=true

Review URL: https://codereview.chromium.org/299443007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@272485 0039d316-1c4b-4281-b951-d872f2087c98

tools/deep_memory_profiler/graph.py

@@ -26,7 +26,7 @@ function turnOn(policy) {
   var data = google.visualization.arrayToDataTable(all_data[policy]);
   var charOptions = {
     title: 'DMP Graph (Policy: ' + policy + ')',
-    vAxis: {title: 'Timestamp',  titleTextStyle: {color: 'red'}},
+    hAxis: {title: 'Timestamp',  titleTextStyle: {color: 'red'}},
     isStacked : true
   };
   var chart = new google.visualization.AreaChart(