[Findit] Add iterator and crash_iterator for delta test

appengine/findit/model/crash/chrome_crash_analysis.py

Index: appengine/findit/model/crash/chrome_crash_analysis.py
diff --git a/appengine/findit/model/crash/chrome_crash_analysis.py b/appengine/findit/model/crash/chrome_crash_analysis.py
index 8e6bd44e4190ba40845d0193356f951a8da54406..fed1df2cfa3c7fac64d102381bebc2c2da1ce50f 100644
--- a/appengine/findit/model/crash/chrome_crash_analysis.py
+++ b/appengine/findit/model/crash/chrome_crash_analysis.py
@@ -17,3 +17,8 @@ class ChromeCrashAnalysis(CrashAnalysis):
     super(ChromeCrashAnalysis, self).Reset()
     self.historical_metadata = None
     self.channel = None
+
+  @property
+  def customized_data(self):
+    return {'historical_metadata': self.historical_metadata,
+            'channel': self.channel}