crrev.com/1956893002 added the "bro" target to gn builds. However it fails to build on Windows because of warnings. The warnings are:

c:\src\chromium4\src\third_party\brotli\enc\cluster.h(91) : error C2220: warning treated as error - no 'object' file generated
c:\src\chromium4\src\third_party\brotli\enc\cluster.h(91) : warning C4701: potentially uninitialized local variable 'p' used

c:\src\chromium4\src\third_party\brotli\enc\hash.h(659): error C2220: warning treated as error - no 'object' file generated
c:\src\chromium4\src\third_party\brotli\enc\hash.h(659): warning C4146: unary minus operator applied to unsigned type, result still unsigned

This happens when building the all target or the 'bro' target. These fixes avoid the warnings, as would suppressing the warnings:

diff --git a/third_party/brotli/enc/cluster.h b/third_party/brotli/enc/cluster.h
index 5054faf..28d7c98 100644
--- a/third_party/brotli/enc/cluster.h
+++ b/third_party/brotli/enc/cluster.h
@@ -63,7 +63,7 @@ void CompareAndPushToQueue(const HistogramType* out,
     idx1 = t;
   }
   bool store_pair = false;
-  HistogramPair p;
+  HistogramPair p = {};
   p.idx1 = idx1;
   p.idx2 = idx2;
   p.cost_diff = 0.5 * ClusterCostDiff(cluster_size[idx1], cluster_size[idx2]);
diff --git a/third_party/brotli/enc/hash.h b/third_party/brotli/enc/hash.h
index 8716863b..e0e8a33 100644
--- a/third_party/brotli/enc/hash.h
+++ b/third_party/brotli/enc/hash.h
@@ -656,7 +656,7 @@ class HashToBinaryTree {
   void Init(int lgwin, size_t position, size_t bytes, bool is_last) {
     if (need_init_) {
       window_mask_ = (1u << lgwin) - 1u;
-      invalid_pos_ = static_cast<uint32_t>(-window_mask_);
+      invalid_pos_ = static_cast<uint32_t>(-static_cast<int32_t>(window_mask_));
       for (uint32_t i = 0; i < kBucketSize; i++) {
         buckets_[i] = invalid_pos_;
       }

Meanwhile the gyp builds are unaffected, apparently because "bro" is not setup to build on gyp, which seems odd, but may be intentional if this is for Android builds only.