tbansal, do you want to look into a fix for this? It sounds somewhat useful for developers.

Raising the priority since one of the web developers contacted me asking for this feature. 

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/172b97a726c5f6b2d7f1883e1b32aa4b979e4cab

commit 172b97a726c5f6b2d7f1883e1b32aa4b979e4cab
Author: Tarun Bansal <tbansal@chromium.org>
Date: Tue Jan 16 06:12:38 2018

Export NQE effective connection type thresholds

The exposed thresholds would be used in Blink
for determing the simulated ECT when latency throttling
is enabled in Devtools.

Bug:  727911 
Change-Id: I276b9ed5c5c0aa74761a4d313f8f00b52aa5ae86
Cq-Include-Trybots: master.tryserver.chromium.android:android_cronet_tester
Reviewed-on: https://chromium-review.googlesource.com/865963
Reviewed-by: Ryan Sturm <ryansturm@chromium.org>
Commit-Queue: Tarun Bansal <tbansal@chromium.org>
Cr-Commit-Position: refs/heads/master@{#529367}
[modify] https://crrev.com/172b97a726c5f6b2d7f1883e1b32aa4b979e4cab/net/nqe/network_quality_estimator_params.cc
[modify] https://crrev.com/172b97a726c5f6b2d7f1883e1b32aa4b979e4cab/net/nqe/network_quality_estimator_params.h

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/65a2abd48ff21a19d3394c1200b9a632a642cdb7

commit 65a2abd48ff21a19d3394c1200b9a632a642cdb7
Author: Tarun Bansal <tbansal@chromium.org>
Date: Mon Jan 22 23:20:19 2018

Override network quality when devtools latency throttling is enabled.

The RTT and ECT is in navigator.connection API is set to the same
value as the throttling value specified.

The setNetworkConnectionInfoOverride() and
setNetworkQualityInfoOverride() have been combined
into a single API.

Bug:  727911 
Change-Id: I7bf809bd4f8bfa8f4256bad2f038ba5123cdc8a1
Reviewed-on: https://chromium-review.googlesource.com/860321
Commit-Queue: Tarun Bansal <tbansal@chromium.org>
Reviewed-by: Josh Karlin <jkarlin@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Reviewed-by: Dmitry Gozman <dgozman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#531052}
[modify] https://crrev.com/65a2abd48ff21a19d3394c1200b9a632a642cdb7/chrome/browser/devtools/devtools_sanity_browsertest.cc
[modify] https://crrev.com/65a2abd48ff21a19d3394c1200b9a632a642cdb7/chrome/test/data/devtools/emulate_network_conditions.html
[modify] https://crrev.com/65a2abd48ff21a19d3394c1200b9a632a642cdb7/third_party/WebKit/LayoutTests/SlowTests
[modify] https://crrev.com/65a2abd48ff21a19d3394c1200b9a632a642cdb7/third_party/WebKit/LayoutTests/http/tests/doc-write-intervention/doc-write-async-third-party-script.html
[modify] https://crrev.com/65a2abd48ff21a19d3394c1200b9a632a642cdb7/third_party/WebKit/LayoutTests/http/tests/doc-write-intervention/doc-write-sync-third-party-script-block-all-conn-types.html
[modify] https://crrev.com/65a2abd48ff21a19d3394c1200b9a632a642cdb7/third_party/WebKit/LayoutTests/http/tests/doc-write-intervention/doc-write-sync-third-party-script-block-effectively-2g-expected.txt
[modify] https://crrev.com/65a2abd48ff21a19d3394c1200b9a632a642cdb7/third_party/WebKit/LayoutTests/http/tests/doc-write-intervention/doc-write-sync-third-party-script-block-effectively-2g.html
[modify] https://crrev.com/65a2abd48ff21a19d3394c1200b9a632a642cdb7/third_party/WebKit/LayoutTests/http/tests/doc-write-intervention/doc-write-sync-third-party-script-block.html
[modify] https://crrev.com/65a2abd48ff21a19d3394c1200b9a632a642cdb7/third_party/WebKit/LayoutTests/http/tests/doc-write-intervention/doc-write-sync-third-party-script-conn-type.html
[modify] https://crrev.com/65a2abd48ff21a19d3394c1200b9a632a642cdb7/third_party/WebKit/LayoutTests/http/tests/doc-write-intervention/doc-write-sync-third-party-script-reload.html
[modify] https://crrev.com/65a2abd48ff21a19d3394c1200b9a632a642cdb7/third_party/WebKit/LayoutTests/http/tests/media/preload-conditions.html
[modify] https://crrev.com/65a2abd48ff21a19d3394c1200b9a632a642cdb7/third_party/WebKit/LayoutTests/http/tests/webfont/font-display-intervention.html
[modify] https://crrev.com/65a2abd48ff21a19d3394c1200b9a632a642cdb7/third_party/WebKit/LayoutTests/media/autoplay-muted-conditions.html
[modify] https://crrev.com/65a2abd48ff21a19d3394c1200b9a632a642cdb7/third_party/WebKit/LayoutTests/netinfo/basic-operation.html
[modify] https://crrev.com/65a2abd48ff21a19d3394c1200b9a632a642cdb7/third_party/WebKit/LayoutTests/netinfo/connection-types.html
[modify] https://crrev.com/65a2abd48ff21a19d3394c1200b9a632a642cdb7/third_party/WebKit/LayoutTests/netinfo/estimate-basic-operation-expected.txt
[modify] https://crrev.com/65a2abd48ff21a19d3394c1200b9a632a642cdb7/third_party/WebKit/LayoutTests/netinfo/estimate-basic-operation.html
[modify] https://crrev.com/65a2abd48ff21a19d3394c1200b9a632a642cdb7/third_party/WebKit/LayoutTests/netinfo/estimate-multiple-frames.html
[modify] https://crrev.com/65a2abd48ff21a19d3394c1200b9a632a642cdb7/third_party/WebKit/LayoutTests/netinfo/estimate-web-worker.html
[modify] https://crrev.com/65a2abd48ff21a19d3394c1200b9a632a642cdb7/third_party/WebKit/LayoutTests/netinfo/multiple-frames.html
[modify] https://crrev.com/65a2abd48ff21a19d3394c1200b9a632a642cdb7/third_party/WebKit/LayoutTests/netinfo/network-quality.html
[modify] https://crrev.com/65a2abd48ff21a19d3394c1200b9a632a642cdb7/third_party/WebKit/LayoutTests/netinfo/resources/netinfo_common.js
[modify] https://crrev.com/65a2abd48ff21a19d3394c1200b9a632a642cdb7/third_party/WebKit/LayoutTests/netinfo/type-change-no-listener-expected.txt
[modify] https://crrev.com/65a2abd48ff21a19d3394c1200b9a632a642cdb7/third_party/WebKit/LayoutTests/netinfo/type-change-no-listener.html
[modify] https://crrev.com/65a2abd48ff21a19d3394c1200b9a632a642cdb7/third_party/WebKit/LayoutTests/netinfo/unregister-during-event.html
[modify] https://crrev.com/65a2abd48ff21a19d3394c1200b9a632a642cdb7/third_party/WebKit/LayoutTests/netinfo/web-worker.html
[modify] https://crrev.com/65a2abd48ff21a19d3394c1200b9a632a642cdb7/third_party/WebKit/Source/core/html/media/HTMLMediaElementTest.cpp
[modify] https://crrev.com/65a2abd48ff21a19d3394c1200b9a632a642cdb7/third_party/WebKit/Source/core/inspector/InspectorNetworkAgent.cpp
[modify] https://crrev.com/65a2abd48ff21a19d3394c1200b9a632a642cdb7/third_party/WebKit/Source/core/loader/FrameFetchContextTest.cpp
[modify] https://crrev.com/65a2abd48ff21a19d3394c1200b9a632a642cdb7/third_party/WebKit/Source/core/testing/Internals.cpp
[modify] https://crrev.com/65a2abd48ff21a19d3394c1200b9a632a642cdb7/third_party/WebKit/Source/core/testing/Internals.h
[modify] https://crrev.com/65a2abd48ff21a19d3394c1200b9a632a642cdb7/third_party/WebKit/Source/core/testing/Internals.idl
[modify] https://crrev.com/65a2abd48ff21a19d3394c1200b9a632a642cdb7/third_party/WebKit/Source/devtools/front_end/Tests.js
[modify] https://crrev.com/65a2abd48ff21a19d3394c1200b9a632a642cdb7/third_party/WebKit/Source/platform/network/DEPS
[modify] https://crrev.com/65a2abd48ff21a19d3394c1200b9a632a642cdb7/third_party/WebKit/Source/platform/network/NetworkStateNotifier.cpp
[modify] https://crrev.com/65a2abd48ff21a19d3394c1200b9a632a642cdb7/third_party/WebKit/Source/platform/network/NetworkStateNotifier.h
[modify] https://crrev.com/65a2abd48ff21a19d3394c1200b9a632a642cdb7/third_party/WebKit/Source/platform/network/NetworkStateNotifierTest.cpp