The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/d2051030e7d9a6ffdfd5f6bde903ec48862b9f49

commit d2051030e7d9a6ffdfd5f6bde903ec48862b9f49
Author: ryansturm <ryansturm@chromium.org>
Date: Thu Jan 12 19:07:20 2017

Adding ExtraRequest info and exposing request to PLM observers

This CL adds a count of requests using DRP and information about
compression. This will allow us to reconsider UMA (e.g., logging UMA for
Mixed content pages (HTTPS pages using DRP from HTTP sub-resources),
logging UMA for <50% of network requests using DRP, >50% of network
requests using DRP, etc.). This will also allow UMA for size of page in
terms of network bytes and in terms of original content length
(precompressed bytes from the origin). This will allow a DRP per-page
data savings histogram as well.

BUG= 679893 

Review-Url: https://codereview.chromium.org/2619243003
Cr-Commit-Position: refs/heads/master@{#443313}

[modify] https://crrev.com/d2051030e7d9a6ffdfd5f6bde903ec48862b9f49/chrome/browser/loader/chrome_resource_dispatcher_host_delegate.cc
[modify] https://crrev.com/d2051030e7d9a6ffdfd5f6bde903ec48862b9f49/chrome/browser/page_load_metrics/metrics_web_contents_observer.cc
[modify] https://crrev.com/d2051030e7d9a6ffdfd5f6bde903ec48862b9f49/chrome/browser/page_load_metrics/metrics_web_contents_observer.h
[modify] https://crrev.com/d2051030e7d9a6ffdfd5f6bde903ec48862b9f49/chrome/browser/page_load_metrics/observers/core_page_load_metrics_observer.cc
[modify] https://crrev.com/d2051030e7d9a6ffdfd5f6bde903ec48862b9f49/chrome/browser/page_load_metrics/observers/core_page_load_metrics_observer.h
[modify] https://crrev.com/d2051030e7d9a6ffdfd5f6bde903ec48862b9f49/chrome/browser/page_load_metrics/page_load_metrics_observer.cc
[modify] https://crrev.com/d2051030e7d9a6ffdfd5f6bde903ec48862b9f49/chrome/browser/page_load_metrics/page_load_metrics_observer.h
[modify] https://crrev.com/d2051030e7d9a6ffdfd5f6bde903ec48862b9f49/chrome/browser/page_load_metrics/page_load_tracker.cc
[modify] https://crrev.com/d2051030e7d9a6ffdfd5f6bde903ec48862b9f49/chrome/browser/page_load_metrics/page_load_tracker.h
[modify] https://crrev.com/d2051030e7d9a6ffdfd5f6bde903ec48862b9f49/chrome/browser/prerender/prerender_browsertest.cc
[modify] https://crrev.com/d2051030e7d9a6ffdfd5f6bde903ec48862b9f49/components/data_reduction_proxy/core/browser/data_reduction_proxy_network_delegate.cc
[modify] https://crrev.com/d2051030e7d9a6ffdfd5f6bde903ec48862b9f49/components/data_reduction_proxy/core/browser/data_reduction_proxy_network_delegate.h
[modify] https://crrev.com/d2051030e7d9a6ffdfd5f6bde903ec48862b9f49/components/data_reduction_proxy/core/common/data_reduction_proxy_util.cc
[modify] https://crrev.com/d2051030e7d9a6ffdfd5f6bde903ec48862b9f49/components/data_reduction_proxy/core/common/data_reduction_proxy_util.h