HPACK optimal Huffman code instrumentation and UMA collection.

net/spdy/hpack_encoder_test.cc

Index: net/spdy/hpack_encoder_test.cc
diff --git a/net/spdy/hpack_encoder_test.cc b/net/spdy/hpack_encoder_test.cc
index 6c8d40988168721867be522f4caa327f118d51bd..33c001c8168fa053c6bfa59331540dbc1e4abeea 100644
--- a/net/spdy/hpack_encoder_test.cc
+++ b/net/spdy/hpack_encoder_test.cc
@@ -57,6 +57,9 @@ class HpackEncoderPeer {
   void TakeString(string* out) {
     encoder_->output_stream_.TakeString(out);
   }
+  void UpdateCharacterCounts(StringPiece str) {
+    encoder_->UpdateCharacterCounts(str);
+  }
   static void CookieToCrumbs(StringPiece cookie,
                              std::vector<StringPiece>* out) {
     Representations tmp;
@@ -420,6 +423,27 @@ TEST_F(HpackEncoderTest, CookieToCrumbs) {
   EXPECT_THAT(out, ElementsAre("foo", "bar", "baz", "bing", ""));
 }
 
+TEST_F(HpackEncoderTest, UpdateCharacterCounts) {
+  std::vector<size_t> counts(256, 0);
+  size_t total_counts = 0;
+  encoder_.SetCharCountsStorage(&counts, &total_counts);
+
+  char kTestString[] = "foo\0\1\xff""boo";
+  peer_.UpdateCharacterCounts(
+      StringPiece(kTestString, arraysize(kTestString) - 1));
+
+  std::vector<size_t> expect(256, 0);
+  expect[static_cast<uint8>('f')] = 1;
+  expect[static_cast<uint8>('o')] = 4;
+  expect[static_cast<uint8>('\0')] = 1;
+  expect[static_cast<uint8>('\1')] = 1;
+  expect[static_cast<uint8>('\xff')] = 1;
+  expect[static_cast<uint8>('b')] = 1;
+
+  EXPECT_EQ(expect, counts);
+  EXPECT_EQ(9u, total_counts);
+}
+
 }  // namespace
 
 }  // namespace net