base: Make RefCountedBytes::TakeVector return ref ptr instead of raw ptr

This patch changes RefCountedBytes::TakeVector to return a ref ptr
instead of a raw pointer. This minimizes the changes of a leak if a
caller forgets to delete it, or forgets to wrap it in a ref ptr.

R=danakj@chromium.org, thakis@chromium.org
TBR=thakis@chromium.org
BUG=595163

Review URL: https://codereview.chromium.org/1803263002

Cr-Commit-Position: refs/heads/master@{#381512}
11 files changed