Increase kNumberOfBitsInFloc to 50

Allow for more flexibility in the FLoC PoC privacy analysis.

Bug: 1111818
Change-Id: I99944a052fe4a5f54e38fe20ce6cd8bc24dc17ba
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2332117Reviewed-by: Yao Xiao <yaoxia@chromium.org>
Reviewed-by: Christian Dullweber <dullweber@chromium.org>
Commit-Queue: Yao Xiao <yaoxia@chromium.org>
Cr-Commit-Position: refs/heads/master@{#793662}

components/federated_learning/floc_id.cc

@@ -14,7 +14,8 @@ namespace {
 
 constexpr char kFlocVersion[] = "1.0.0";
 
-constexpr size_t kNumberOfBitsInFloc = 16;
+// This is only for experimentation and won't be served to websites.
+constexpr size_t kNumberOfBitsInFloc = 50;
 static_assert(kNumberOfBitsInFloc > 0 &&
                   kNumberOfBitsInFloc <= std::numeric_limits<uint64_t>::digits,
               "Number of bits in the floc id must be greater than 0 and no "