Send UMA Stats for update engine error codes.

With the latest addition of new optional security checks for the update
manifest and operations checked in, we now want to track the number of
failures, if any, over time to help us decide when it is safe to make
the new security checks mandatory. This CL adds the UMA metric for
reporting the new (as well as the old) error codes to UMA for the first
time.

There's no change to the existing errors that are being sent to Omaha.
Due to UMA restrictions, some Omaha codes will be aggregated when being
sent to UMA.

BUG=chromium-os:34299
TEST=Unit tests pass, tested on real ZGB, all stats show up in
     chrome://histograms correctly for both dev mode and normal mode.
Change-Id: I3ce4645636311cedbb33f601e775951966c0a545
Reviewed-on: https://gerrit.chromium.org/gerrit/36408
Commit-Ready: Jay Srinivasan <jaysri@chromium.org>
Reviewed-by: Jay Srinivasan <jaysri@chromium.org>
Tested-by: Jay Srinivasan <jaysri@chromium.org>
diff --git a/download_action_unittest.cc b/download_action_unittest.cc
index fb9acf7..81ea589 100644
--- a/download_action_unittest.cc
+++ b/download_action_unittest.cc
@@ -145,7 +145,7 @@
                                                       data.size(),
                                                       NULL);
   // takes ownership of passed in HttpFetcher
-  DownloadAction download_action(&prefs, http_fetcher);
+  DownloadAction download_action(&prefs, NULL, http_fetcher);
   download_action.SetTestFileWriter(&writer);
   BondActions(&feeder_action, &download_action);
   DownloadActionDelegateMock download_delegate;
@@ -255,7 +255,7 @@
     InstallPlan install_plan(false, "", 0, "", 0, "", temp_file.GetPath(), "");
     feeder_action.set_obj(install_plan);
     PrefsMock prefs;
-    DownloadAction download_action(&prefs,
+    DownloadAction download_action(&prefs, NULL,
                                    new MockHttpFetcher(&data[0],
                                                        data.size(),
                                                        NULL));
@@ -363,7 +363,8 @@
   ObjectFeederAction<InstallPlan> feeder_action;
   feeder_action.set_obj(install_plan);
   PrefsMock prefs;
-  DownloadAction download_action(&prefs, new MockHttpFetcher("x", 1, NULL));
+  DownloadAction download_action(&prefs, NULL,
+                                 new MockHttpFetcher("x", 1, NULL));
   download_action.SetTestFileWriter(&writer);
 
   DownloadActionTestAction test_action;
@@ -397,7 +398,8 @@
   ObjectFeederAction<InstallPlan> feeder_action;
   feeder_action.set_obj(install_plan);
   PrefsMock prefs;
-  DownloadAction download_action(&prefs, new MockHttpFetcher("x", 1, NULL));
+  DownloadAction download_action(&prefs, NULL,
+                                 new MockHttpFetcher("x", 1, NULL));
   download_action.SetTestFileWriter(&writer);
 
   BondActions(&feeder_action, &download_action);