Remove unused function and its corresponded test. No behavior change.

Merge internal change: 206330851

Bug: 788385
Change-Id: I0a0823638aa9692024751a80e6470bb11ddfeb3c
Reviewed-on: https://chromium-review.googlesource.com/1153387Reviewed-by: Zhongyi Shi <zhongyi@chromium.org>
Commit-Queue: Renjie Tang <renjietang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#578870}

net/third_party/quic/core/quic_data_writer.cc

@@ -48,17 +48,6 @@ bool QuicDataWriter::WriteUInt64(uint64_t value) {
   return WriteBytes(&value, sizeof(value));
 }
 
-bool QuicDataWriter::WriteUInt8AtOffset(uint8_t value, size_t offset) {
-  if (offset > length_) {
-    return false;
-  }
-  size_t old_length = length_;
-  length_ = offset;
-  bool result = WriteBytes(&value, sizeof(value));
-  length_ = old_length;
-  return result;
-}
-
 bool QuicDataWriter::WriteBytesToUInt64(size_t num_bytes, uint64_t value) {
   if (num_bytes > sizeof(value)) {
     return false;

net/third_party/quic/core/quic_data_writer.h

@@ -76,10 +76,6 @@ class QUIC_EXPORT_PRIVATE QuicDataWriter {
   // is too large to encode.
   static int GetVarInt62Len(uint64_t value);
 
-  // Writes |value| to the position |offset| from the start of the data.
-  // |offset| must be less than the current length of the writer.
-  bool WriteUInt8AtOffset(uint8_t value, size_t offset);
-
   // Writes least significant |num_bytes| of a 64-bit unsigned integer in the
   // correct byte order.
   bool WriteBytesToUInt64(size_t num_bytes, uint64_t value);

net/third_party/quic/core/quic_data_writer_test.cc

@@ -567,23 +567,6 @@ TEST_P(QuicDataWriterTest, WriteBytes) {
   }
 }
 
-TEST_P(QuicDataWriterTest, WriteUInt8AtOffset) {
-  char bytes[] = {'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H'};
-  char buf[QUIC_ARRAYSIZE(bytes)];
-  for (unsigned int i = 0; i < QUIC_ARRAYSIZE(bytes); ++i) {
-    QuicDataWriter writer(QUIC_ARRAYSIZE(buf), buf, GetParam().endianness);
-    EXPECT_TRUE(writer.WriteBytes(bytes, QUIC_ARRAYSIZE(bytes)));
-    EXPECT_TRUE(writer.WriteUInt8AtOffset('I', i));
-    for (unsigned int j = 0; j < QUIC_ARRAYSIZE(bytes); ++j) {
-      if (j == i) {
-        EXPECT_EQ('I', buf[j]);
-      } else {
-        EXPECT_EQ(bytes[j], buf[j]);
-      }
-    }
-  }
-}
-
 const int kVarIntBufferLength = 1024;
 
 // Encodes and then decodes a specified value, checks that the