SafeBrowsing: Create a custom histogram enum for V4 GetHash results.

tools/metrics/histograms/histograms.xml

Index: tools/metrics/histograms/histograms.xml
diff --git a/tools/metrics/histograms/histograms.xml b/tools/metrics/histograms/histograms.xml
index 6ef1418e830770d0db797bfe4775f3d024b0c155..e017c3a93af4706e68dc367bb54af74244edaa9d 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -40689,18 +40689,12 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
-<histogram name="SafeBrowsing.GetV4HashResult" enum="SB2GetHashResult">
+<histogram name="SafeBrowsing.GetV4HashResult"

[rkaplow, 2016/02/03 22:51:05]

can you create a new histogram and obsolete the current one? The new version
will be incompatible.

As well, can you verify no other histograms are using the SB2GetHashResult enum
since you're making changes to the enum in the code.

[kcarattini, 2016/02/03 22:53:41]

Since the code is not live this histogram never collected any data, so it is
fine to change the enum.

There is another histogram using SB2GetHashResult which is why I have not
removed it.

+    enum="SafeBrowsingGetV4HashResult">
   <owner>kcarattini@chromium.org</owner>
   <summary>
-    Track return status from V4 GetHash attempts (STATUS_200, STATUS_204,
-    NETWORK_ERROR, HTTP_ERROR, BACKOFF_ERROR, PARSE_ERROR, NETWORK_ERROR,
-    HTTP_ERROR, BACKOFF_ERROR and MIN_WAIT_DURATION_ERROR), whether parsing a
-    200 result failed (PARSE_ERROR), and dispensation of returned values (EMPTY,
-    HIT, MISS). EMPTY means the response had no full hashes, and should contain
-    all of the 204 responses plus all *_ERROR cases.  HIT means that one of the
-    full hashes matched. MISS means that none of the hashes matched (there was a
-    prefix collision). The buckets of this histogram overlap, so the counts
-    cannot be used as percentages.
+    Track return status from V4 GetHash attempts. The buckets of this histogram
+    overlap, so the counts cannot be used as percentages.
   </summary>
 </histogram>
 
@@ -76408,6 +76402,15 @@ To add a new entry, add it with any value and run test to compute valid value.
   <int value="1" label="Kill (He's dead, Jim!)"/>
 </enum>
 
+<enum name="SafeBrowsingGetV4HashResult" type="int">
+  <int value="0" label="STATUS_200"/>
+  <int value="1" label="PARSE_ERROR (subset of STATUS_200)"/>
+  <int value="2" label="NETWORK_ERROR"/>
+  <int value="3" label="HTTP_ERROR"/>
+  <int value="4" label="BACKOFF_ERROR"/>
+  <int value="5" label="MIN_WAIT_DURATION_ERROR"/>
+</enum>
+
 <enum name="SafeBrowsingParseV4HashResult" type="int">
   <int value="0" label="PARSE_FROM_STRING_ERROR"/>
   <int value="1" label="UNEXPECTED_THREAT_ENTRY_TYPE_ERROR"/>