Rice decode removals and additions and use them to update the store.

components/safe_browsing_db/v4_store.h

Index: components/safe_browsing_db/v4_store.h
diff --git a/components/safe_browsing_db/v4_store.h b/components/safe_browsing_db/v4_store.h
index 310004dc5df5e0e93edbb60f9ed03557f49e1107..f7e2d126bac4f29e51ddf5ce0b1b5c9d5e6176d8 100644
--- a/components/safe_browsing_db/v4_store.h
+++ b/components/safe_browsing_db/v4_store.h
@@ -133,7 +133,16 @@ enum ApplyUpdateResult {
 
   // One of more index(es) in removals field of the response is greater than
   // the number of hash prefixes currently in the (old) store.
-  REMOVALS_INDEX_TOO_LARGE = 7,
+  REMOVALS_INDEX_TOO_LARGE_FAILURE = 7,
+
+  // Failed to decode the Rice-encoded additions/removals field.
+  RICE_DECODING_FAILURE = 8,
+
+  // Compression type other than RAW and RICE for additions.

[Nathan Parker, 2016/08/02 23:43:31]

Nit: This might be a bit more detailed error reporting than needed, since the
probability of needing to differentiate these is very small.  Could be rolled
into a "invalid_update_proto_failre."  But your choice.

[vakh (use Gerrit instead), 2016/08/03 06:54:53]

I think it may be useful in the beginning as we roll out this code to verify
that things are working as expected pr to identify which parts of the update are
not getting processed as expected.

+  UNEXPECTED_COMPRESSION_TYPE_ADDITIONS_FAILURE = 9,
+
+  // Compression type other than RAW and RICE for removals.
+  UNEXPECTED_COMPRESSION_TYPE_REMOVALS_FAILURE = 10,
 
   // Memory space for histograms is determined by the max.  ALWAYS
   // ADD NEW VALUES BEFORE THIS ONE.
@@ -238,6 +247,11 @@ class V4Store {
                            TestHashPrefixExistsInMapWithDifferentSizes);
   FRIEND_TEST_ALL_PREFIXES(V4StoreTest,
                            TestHashPrefixDoesNotExistInMapWithDifferentSizes);
+  FRIEND_TEST_ALL_PREFIXES(V4StoreTest,
+                           TestAdditionsWithRiceEncodingFailsWithInvalidInput);
+  FRIEND_TEST_ALL_PREFIXES(V4StoreTest, TestAdditionsWithRiceEncodingSucceeds);
+  FRIEND_TEST_ALL_PREFIXES(V4StoreTest, TestRemovalsWithRiceEncodingSucceeds);
+  friend class V4StoreTest;

[Nathan Parker, 2016/08/02 23:43:31]

Does this obviate the need for all the friends?  It's a lot of friends.

[vakh (use Gerrit instead), 2016/08/03 06:54:52]

Unfortunately not.
The individual tests are not a part of this class so making this class a  friend
is not enough.
That's why we have to use the macro: FRIEND_TEST_ALL_PREFIXES

 
   // If |prefix_size| is within expected range, and |raw_hashes| is not invalid,
   // then it sets |raw_hashes| as the value at key |prefix_size| in