Add UMA metric for GetHash parsing errors.

chrome/browser/safe_browsing/protocol_manager.h

Index: chrome/browser/safe_browsing/protocol_manager.h
diff --git a/chrome/browser/safe_browsing/protocol_manager.h b/chrome/browser/safe_browsing/protocol_manager.h
index 8d3c1191ee31cca201514be8e1954a173377c1c3..e595b1414dffef71719ff06ba54eb2ab6afc80f8 100644
--- a/chrome/browser/safe_browsing/protocol_manager.h
+++ b/chrome/browser/safe_browsing/protocol_manager.h
@@ -179,6 +179,33 @@ class SafeBrowsingProtocolManager : public net::URLFetcherDelegate,
   // Record a V4 GetHash result.
   static void RecordGetV4HashResult(ResultType result_type);
 
+  // Enumerate V4 parsing failures for histogramming purposes.  DO NOT CHANGE

[Nathan Parker, 2016/01/15 19:34:43]

This could all go in a n anonymous namespace in the .cc file, since noone
outside of that needs access to it.

[kcarattini, 2016/01/20 04:02:05]

Done.

+  // THE ORDERING OF THESE VALUES.
+  enum ParseResultType {
+    // Error parsing the protocol buffer from a string.
+    PARSE_FROM_STRING_ERROR,

[Nathan Parker, 2016/01/15 19:34:42]

I like to add "= 1.." to each so that you can more easily verify they match the
.xml, and it protects a bit more from accidental reordering.

[kcarattini, 2016/01/20 04:02:05]

Done.

+
+    // A match in the response had an unexpected THREAT_ENTRY_TYPE.
+    UNEXPECTED_THREAT_ENTRY_TYPE_ERROR,
+
+    // A match in the response had an unexpected THREAT_TYPE.
+    UNEXPECTED_THREAT_TYPE_ERROR,
+
+    // A match in the response had an unexpected PLATFORM_TYPE.
+    UNEXPECTED_PLATFORM_TYPE_ERROR,
+
+    // A match in teh response contained no metadata where metadata was
+    // expected.
+    NO_METADATA_ERROR,
+
+    // Memory space for histograms is determined by the max.  ALWAYS
+    // ADD NEW VALUES BEFORE THIS ONE.
+    PARSE_GET_HASH_RESULT_MAX
+  };
+
+  // Record parsing errors of a GetHash result.
+  static void RecordParseGetHashResult(ParseResultType result_type);
+
   // Record HTTP response code when there's no error in fetching an HTTP
   // request, and the error code, when there is.
   // |metric_name| is the name of the UMA metric to record the response code or