Disable SDCH by default across the product. Embedders - whether Cronet or //content embedders - will be able to enable it, until we can reach broader internal consensus to fully remove the code.

See also https://groups.google.com/a/chromium.org/d/msg/blink-dev/nQl0ORHy7sw/HNpR96sqAgAJ

 Issue 687182  has been merged into this issue.

Moving to M59 due to bad interactions with the cache.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/4152e1751a735f2c0f2cffc30976f9c5ed233f95

commit 4152e1751a735f2c0f2cffc30976f9c5ed233f95
Author: rdsmith <rdsmith@chromium.org>
Date: Fri Mar 31 12:29:44 2017

Disable SDCH by Default

Disable SDCH in Chrome. It remains accessible via either explicit
initialization of an SdchManager/SdchOwner or through the use of
URLRequestContextBuilder's set_sdch_enabled(true)

This does not disable the SDCH netlog panel, as there may be SDCH net-internals dumps that need to be examined from earlier versions of Chrome.

BUG= 696815 

patch from issue 2720613006 at patchset 1 (http://crrev.com/2720613006#ps1)
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:closure_compilation

Review-Url: https://codereview.chromium.org/2785493003
Cr-Commit-Position: refs/heads/master@{#461100}

[modify] https://crrev.com/4152e1751a735f2c0f2cffc30976f9c5ed233f95/chrome/browser/net/sdch_browsertest.cc
[modify] https://crrev.com/4152e1751a735f2c0f2cffc30976f9c5ed233f95/chrome/browser/profiles/off_the_record_profile_io_data.cc
[modify] https://crrev.com/4152e1751a735f2c0f2cffc30976f9c5ed233f95/chrome/browser/profiles/off_the_record_profile_io_data.h
[modify] https://crrev.com/4152e1751a735f2c0f2cffc30976f9c5ed233f95/chrome/browser/profiles/profile_impl_io_data.cc
[modify] https://crrev.com/4152e1751a735f2c0f2cffc30976f9c5ed233f95/chrome/browser/profiles/profile_impl_io_data.h
[modify] https://crrev.com/4152e1751a735f2c0f2cffc30976f9c5ed233f95/chrome/browser/resources/net_internals/sdch_view.js
[modify] https://crrev.com/4152e1751a735f2c0f2cffc30976f9c5ed233f95/chrome/common/chrome_constants.cc
[modify] https://crrev.com/4152e1751a735f2c0f2cffc30976f9c5ed233f95/chrome/common/chrome_constants.h
[modify] https://crrev.com/4152e1751a735f2c0f2cffc30976f9c5ed233f95/chrome/test/data/webui/net_internals/log_util.js
[modify] https://crrev.com/4152e1751a735f2c0f2cffc30976f9c5ed233f95/chrome/test/data/webui/net_internals/sdch_view.js
[modify] https://crrev.com/4152e1751a735f2c0f2cffc30976f9c5ed233f95/ios/chrome/browser/browser_state/chrome_browser_state_impl_io_data.h
[modify] https://crrev.com/4152e1751a735f2c0f2cffc30976f9c5ed233f95/ios/chrome/browser/browser_state/chrome_browser_state_impl_io_data.mm
[modify] https://crrev.com/4152e1751a735f2c0f2cffc30976f9c5ed233f95/ios/chrome/browser/browser_state/off_the_record_chrome_browser_state_io_data.h
[modify] https://crrev.com/4152e1751a735f2c0f2cffc30976f9c5ed233f95/ios/chrome/browser/browser_state/off_the_record_chrome_browser_state_io_data.mm