Safebrowsing: change gethash caching to match api 2.3 rules, fix some corner cases.

chrome/browser/safe_browsing/protocol_parser.cc

Index: chrome/browser/safe_browsing/protocol_parser.cc
diff --git a/chrome/browser/safe_browsing/protocol_parser.cc b/chrome/browser/safe_browsing/protocol_parser.cc
index 1fb64ef7521eb8ac9a62748d8eec75e055ad4eab..450bd12c7a39f887ffdddff32b2b1f738f9647ce 100644
--- a/chrome/browser/safe_browsing/protocol_parser.cc
+++ b/chrome/browser/safe_browsing/protocol_parser.cc
@@ -66,7 +66,8 @@ bool SafeBrowsingProtocolParser::ParseGetHash(
 
     SBFullHashResult full_hash;
     full_hash.list_name = cmd_parts[0];
-    full_hash.add_chunk_id = atoi(cmd_parts[1].c_str());
+    // Ignore cmd_parts[1] (add_chunk_id), as we no longer use it with SB 2.3
+    // caching rules.
     int full_hash_len = atoi(cmd_parts[2].c_str());
 
     // Ignore hash results from lists we don't recognize.