Introduce BufferingDataPipeWriter

This CL introduces BufferingDataPipeWriter which is conceptually the
writer end of a data pipe accompanied with buffers. This class is planned
to be used for fetch API support for preloading.

Bug: 652228
Change-Id: I538de868ff77f772e826345c700c654763659e03
Reviewed-on: https://chromium-review.googlesource.com/548517
Commit-Queue: Yutaka Hirano <yhirano@chromium.org>
Reviewed-by: Takashi Toyoshima <toyoshim@chromium.org>
Cr-Commit-Position: refs/heads/master@{#482619}
4 files changed