Stop updating SafeBrowsing download hash list.

chrome/browser/safe_browsing/safe_browsing_database.cc

Index: chrome/browser/safe_browsing/safe_browsing_database.cc
diff --git a/chrome/browser/safe_browsing/safe_browsing_database.cc b/chrome/browser/safe_browsing/safe_browsing_database.cc
index 6721f10cd508caafb2efc9d108de85c1912267b9..ea02ff6bfbca8e89be5fed149c6606bb1a5e9cbb 100644
--- a/chrome/browser/safe_browsing/safe_browsing_database.cc
+++ b/chrome/browser/safe_browsing/safe_browsing_database.cc
@@ -1069,6 +1069,14 @@ bool SafeBrowsingDatabaseNew::UpdateStarted(
     download_listnames.push_back(safe_browsing_util::kBinUrlList);
     download_listnames.push_back(safe_browsing_util::kBinHashList);

[Scott Hess - ex-Googler, 2012/01/07 02:27:56]

Can you just drop the above line?  The csd case below implies that you can do
it, as long as it doesn't change the positioning w/in the vector. 
UpdateChunkRanges() will still pull all of the data, but the final loop will
only process the adds and subs at index 0.

If you're at the right point in the transaction, deleting could be done like:

void DeleteChunksFromStore(SafeBrowsingStore* store, int listid){
  std::vector<int> chunks;

  store->GetAddChunks(&chunks);
  for (std::vector<int>::const_iterator iter = chunks.begin();
       iter != chunks.end(); ++iter) {
    if (GetListIdBit(*iter) == listid)
      store->DeleteAddChunk(*iter);
  }

  store->GetSubChunks(&chunks);
  for (std::vector<int>::const_iterator iter = chunks.begin();
       iter != chunks.end(); ++iter) {
    if (GetListIdBit(*iter) == listid)
      store->DeleteSubChunk(*iter);
  }
}

Since that will pull all the chunks every time (relatively cheap, but still),
there might be some advantage to calling it after UpdateChunkRanges() returns
results which show that there actually are chunks in there.  But I suspect it'd
be a trivial trivial trivial savings.

[mattm, 2012/01/07 03:18:12]

If we remove that, GetChunkRanges fails because it expects to receive the output
buffer of the correct size.  We could make it more permissive, but not sure
that's better since it could also hide accidental code errors.
Thanks! I was thinking about that at the wrong level I think :)
Added.

     UpdateChunkRanges(download_store_.get(), download_listnames, lists);
+    DCHECK_EQ(lists->back().name,
+              std::string(safe_browsing_util::kBinHashList));
+    // Remove kBinHashList entry so that we do not request updates for it from
+    // the server.  The existing data will still be retained by
+    // SafeBrowsingStoreFile::DoUpdate.
+    // TODO(mattm): write some code to remove the kBinHashList data from the
+    // file?
+    lists->pop_back();
   }
 
   if (csd_whitelist_store_.get()) {