Merge "GC step 2. Finding garbage bigram entries."

native/jni/src/suggest/core/dictionary/bigram_dictionary.cpp

native/jni/src/suggest/core/dictionary/multi_bigram_map.h

...est/core/policy/dictionary_structure_with_buffer_policy.h

native/jni/src/suggest/core/suggest.cpp

...suggest/policyimpl/dictionary/bigram/bigram_list_policy.h

...cyimpl/dictionary/bigram/bigram_list_read_write_utils.cpp

...licyimpl/dictionary/bigram/bigram_list_read_write_utils.h

...licyimpl/dictionary/bigram/dynamic_bigram_list_policy.cpp

...policyimpl/dictionary/bigram/dynamic_bigram_list_policy.h

...mpl/dictionary/dynamic_patricia_trie_gc_event_listeners.h

...licyimpl/dictionary/dynamic_patricia_trie_node_reader.cpp

...policyimpl/dictionary/dynamic_patricia_trie_node_reader.h

...st/policyimpl/dictionary/dynamic_patricia_trie_policy.cpp

...gest/policyimpl/dictionary/dynamic_patricia_trie_policy.h

...yimpl/dictionary/dynamic_patricia_trie_reading_helper.cpp

...icyimpl/dictionary/dynamic_patricia_trie_reading_helper.h

...yimpl/dictionary/dynamic_patricia_trie_writing_helper.cpp

...rc/suggest/policyimpl/dictionary/patricia_trie_policy.cpp

.../src/suggest/policyimpl/dictionary/patricia_trie_policy.h