Tracing V2: Fully-functional plugin.

components/tracing/test/fake_scattered_buffer.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "components/tracing/test/fake_scattered_buffer.h"
 
 #include <string.h>
 
 #include "base/strings/string_number_conversions.h"
 #include "testing/gtest/include/gtest/gtest.h"
@@ skipping 11 matching lines @@
   uint8_t* begin = chunk.get();
   memset(begin, 0, chunk_size_);
   chunks_.push_back(std::move(chunk));
   return {begin, begin + chunk_size_};
 }
 
 std::string FakeScatteredBuffer::GetChunkAsString(int chunk_index) {
   return base::HexEncode(chunks_[chunk_index].get(), chunk_size_);
 }
 
+void FakeScatteredBuffer::GetBytes(size_t start, size_t length, uint8_t* buf) {
+  ASSERT_LE(start + length, chunks_.size() * chunk_size_);
+  for (size_t pos = 0; pos < length; ++pos) {
+    size_t chunk_index = (start + pos) / chunk_size_;
+    size_t chunk_offset = (start + pos) % chunk_size_;
+    buf[pos] = chunks_[chunk_index].get()[chunk_offset];
+  }
+}
+
 std::string FakeScatteredBuffer::GetBytesAsString(size_t start, size_t length) {
   std::string hexstr;
   EXPECT_LE(start + length, chunks_.size() * chunk_size_);

[Primiano Tucci (use gerrit), 2016/08/25 10:31:51]

at this point can you rewrite this in terms of GetBytes + hex serialization?
There feels to be quite some duplication. 
Fine to remove the <OUT OF BOUND> if you have the assert_le.

   for (size_t pos = start; pos < start + length; ++pos) {
     const size_t chunk_idx = pos / chunk_size_;
     const size_t chunk_off = pos % chunk_size_;
     if (chunk_idx >= chunks_.size()) {
       hexstr += " <OUT OF BOUND @ pos=" + base::SizeTToString(pos) + ">";
       return hexstr;
     }
     hexstr += base::HexEncode(&chunks_[chunk_idx].get()[chunk_off], 1);
   }
   return hexstr;
 }
 
 }  // namespace v2
 }  // namespace tracing