add feature statistics trigger for scratches

platform/lang-impl/src/com/intellij/ide/scratch/NewScratchFileAction.java

@@ -15,6 +15,7 @@
  */
 package com.intellij.ide.scratch;
 
+import com.intellij.featureStatistics.FeatureUsageTracker;
 import com.intellij.lang.DependentLanguage;
 import com.intellij.lang.InjectableLanguage;
 import com.intellij.lang.Language;
@@ -71,6 +72,7 @@ public class NewScratchFileAction extends AnAction implements DumbAware {
     ListPopup popup = buildLanguagePopup(previous, new Consumer<Language>() {
       @Override
       public void consume(Language language) {
+        FeatureUsageTracker.getInstance().triggerFeatureUsed("scratch");
         VirtualFile file = ScratchpadManager.getInstance(project).createScratchFile(language);
         FileEditorManager.getInstance(project).openFile(file, true);
       }

platform/platform-resources-en/src/messages/FeatureStatisticsBundle.properties

@@ -122,3 +122,5 @@ find.completion=Completion in Find Bar
 switcher=Switcher
 dir.diff=Directory Diff
 jar.diff=JAR Files Diff
+
+scratch=New scratch file

platform/platform-resources-en/src/tips/Scratch.html

@@ -0,0 +1,10 @@
+<html>
+<head>
+  <link rel="stylesheet" type="text/css" href="css/tips.css">
+</head>
+<body>
+<p>
+  Scratch files allows you experiment and prototype right in the editor, 
+  without creating any project files.</p>
+</body>
+</html>

resources/src/ProductivityFeaturesRegistry.xml

@@ -246,6 +246,12 @@
       min-usage-count="10"
       first-show="2"
       successive-show="4"/>
+    <feature
+      id="scratch"
+      tip-file="Scratch.html"
+      min-usage-count="10"
+      first-show="2"
+      successive-show="3"/>
   </group>
 
   <group id="codeassists">