Use 64-bit for seeded integer hashes

R=petermarshall@chromium.org

Bug: chromium:680662
Change-Id: If48d1043dbe1e1bb695ec890c23e103a6cacf2d4
Reviewed-on: https://chromium-review.googlesource.com/1244220
Commit-Queue: Yang Guo <yangguo@chromium.org>
Reviewed-by: Peter Marshall <petermarshall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56271}

src/utils.h

@@ -508,11 +508,11 @@ inline uint32_t ComputeLongHash(uint64_t key) {
   hash = hash ^ (hash >> 11);
   hash = hash + (hash << 6);
   hash = hash ^ (hash >> 22);
-  return static_cast<uint32_t>(hash);
+  return static_cast<uint32_t>(hash & 0x3fffffff);
 }
 
 inline uint32_t ComputeSeededHash(uint32_t key, uint64_t seed) {
-  return ComputeUnseededHash(key ^ static_cast<uint32_t>(seed));
+  return ComputeLongHash(static_cast<uint64_t>(key) ^ seed);
 }
 
 inline uint32_t ComputePointerHash(void* ptr) {