I'm interested in trying this out, but i don't exactly understand those steps.

- Migrate all Blink unittests that use CreateURLLoader / GetURLLoaderMockFactory over TestingPlatformSupport or FetchTestingPlatformSupport (like what platform tests do)

Do I understand correctly that there is no Blink unittest using CreateURLLoader? The usage of  GetURLLoaderMockFactory in unittests with  Platform::Current() such as [1], how to migrate?

- Deprecate TestBlinkPlatformSupport::GetURLLoaderMockFactory() (all test code can just use TestingPlatformSupport's one)

Has it deprecated?

- Remove all the URLLoaderMockFactory related code from content and WebKit/public (e.g. Platform::GetURLLoaderMockFactory and WebURLLoaderMockFactory)

Does it mean remove function Platform::GetURLLoaderMockFactory [2]

[1] https://cs.chromium.org/chromium/src/third_party/WebKit/Source/core/loader/DocumentLoaderTest.cpp?q=GetURLLoaderMockFactory&dr=C&l=78
[2] https://cs.chromium.org/chromium/src/third_party/WebKit/public/platform/Platform.h?dr=C&l=471

I'm reviewing one CL that is related to this bug. The migration steps I understand are

1. Replace all Platform::Current()->GetURLLoaderMockFactory() calls with TestingPlatformSupport's GetURLLoaderMockFactory().
2. Deprecate TestBlinkPlatformSupport::GetURLLoaderMockFactory() and TestBlinkWebUnitTestSupport::GetURLLoaderMockFactory() that have been called via Platform::Current() until 1. is done.
3. Deprecate Platform::GetURLLoaderMockFactory interface.
4. Move required WebURLLoaderMockFactory functionalities into TestingPlatformSupport, and deprecate WebURLLoaderMockFactory.

All steps can be done incrementally, and contributions would be very appreciated.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/00b3e3e1f5b222b72e4f0d7e33fff59aa0eb4783

commit 00b3e3e1f5b222b72e4f0d7e33fff59aa0eb4783
Author: Yeol <peary2@gmail.com>
Date: Wed Sep 13 09:58:21 2017

Replace Platform::Current() with TestingPlatformSupport to call GetURLLoaderMockFactory.

It's modified in core/frame and /platform.

Bug: 751425
Change-Id: Ibe09bbd6debbcfcbef5624f98ec486770d97698c
Reviewed-on: https://chromium-review.googlesource.com/611742
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Reviewed-by: Takashi Toyoshima <toyoshim@chromium.org>
Commit-Queue: Takashi Toyoshima <toyoshim@chromium.org>
Cr-Commit-Position: refs/heads/master@{#501581}
[modify] https://crrev.com/00b3e3e1f5b222b72e4f0d7e33fff59aa0eb4783/third_party/WebKit/Source/core/frame/BrowserControlsTest.cpp
[modify] https://crrev.com/00b3e3e1f5b222b72e4f0d7e33fff59aa0eb4783/third_party/WebKit/Source/core/frame/FrameSerializerTest.cpp
[modify] https://crrev.com/00b3e3e1f5b222b72e4f0d7e33fff59aa0eb4783/third_party/WebKit/Source/core/frame/MHTMLTest.cpp
[modify] https://crrev.com/00b3e3e1f5b222b72e4f0d7e33fff59aa0eb4783/third_party/WebKit/Source/platform/loader/fetch/ResourceFetcherTest.cpp

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/485f45aa3f11bfcce18d341443edf9a031efe71e

commit 485f45aa3f11bfcce18d341443edf9a031efe71e
Author: Yeol <peary2@gmail.com>
Date: Fri Sep 15 11:36:32 2017

Replace Platform::Current() with TestingPlatformSupport to call GetURLLoaderMockFactory.

It's modified in WebKit/Source/modules.

Bug: 751425
Change-Id: I7c35f10947b137c8a2674eabdb0ff977b1c2f238
Reviewed-on: https://chromium-review.googlesource.com/654022
Reviewed-by: Takashi Toyoshima <toyoshim@chromium.org>
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Commit-Queue: Kentaro Hara <haraken@chromium.org>
Cr-Commit-Position: refs/heads/master@{#502225}
[modify] https://crrev.com/485f45aa3f11bfcce18d341443edf9a031efe71e/third_party/WebKit/Source/modules/indexeddb/IDBRequestTest.cpp
[modify] https://crrev.com/485f45aa3f11bfcce18d341443edf9a031efe71e/third_party/WebKit/Source/modules/indexeddb/IDBTransactionTest.cpp
[modify] https://crrev.com/485f45aa3f11bfcce18d341443edf9a031efe71e/third_party/WebKit/Source/modules/notifications/NotificationImageLoaderTest.cpp
[modify] https://crrev.com/485f45aa3f11bfcce18d341443edf9a031efe71e/third_party/WebKit/Source/modules/notifications/NotificationResourcesLoaderTest.cpp
[modify] https://crrev.com/485f45aa3f11bfcce18d341443edf9a031efe71e/third_party/WebKit/Source/modules/wake_lock/ScreenWakeLockTest.cpp

Let me take a tentative ownership to mark the bug status as Started.
Actual code owner is Yoel as you see in the commit logs, but only project members can be assigned to the owner by another people, IIUC.

Yoel, if you can edit the owner label by yourself, please update it to be you.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/017b79e68acccf53f361d80168cb85daa9c4a8b4

commit 017b79e68acccf53f361d80168cb85daa9c4a8b4
Author: Kinuko Yasuda <kinuko@chromium.org>
Date: Tue Oct 24 17:46:10 2017

Always use per-frame / per-context URLLoaderFactory via WebURLLoaderFactory

Replacing CreateURLLoader() in following places with CreateURLLoaderFactory:
- WebFrameClient (e.g. RenderFrameImpl)
- WebWorkerFetchContext
- Platform

And always try to use the created URLLoaderFactory for the context (e.g.
Frame, Worker context or FetchContext).

Remaining TODOs:
- We should remove the WebURLLoaderFactoryWithMock impl in //content and all
  test harness should create its own blink::WebURLLoaderFactoryWithMock
  w/o going though Platform layer (crbug.com/751425)
- Once we finalize the MojoLoading migration WebURLLoaderFactory should be
  replaced with mojo::URLLoaderFactory
- (More code cleanup around throttles etc)

Bug:  712913 , 751425
Change-Id: I4249fd9cf5b056802dc57138e9555d5d9c00122a
Reviewed-on: https://chromium-review.googlesource.com/708074
Commit-Queue: Kinuko Yasuda <kinuko@chromium.org>
Reviewed-by: Takashi Toyoshima <toyoshim@chromium.org>
Reviewed-by: Jochen Eisinger <jochen@chromium.org>
Reviewed-by: Tsuyoshi Horo <horo@chromium.org>
Reviewed-by: Yutaka Hirano <yhirano@chromium.org>
Cr-Commit-Position: refs/heads/master@{#511202}
[modify] https://crrev.com/017b79e68acccf53f361d80168cb85daa9c4a8b4/components/plugins/renderer/webview_plugin.cc
[modify] https://crrev.com/017b79e68acccf53f361d80168cb85daa9c4a8b4/components/plugins/renderer/webview_plugin.h
[modify] https://crrev.com/017b79e68acccf53f361d80168cb85daa9c4a8b4/components/printing/renderer/print_render_frame_helper.cc
[modify] https://crrev.com/017b79e68acccf53f361d80168cb85daa9c4a8b4/content/ppapi_plugin/ppapi_blink_platform_impl.cc
[modify] https://crrev.com/017b79e68acccf53f361d80168cb85daa9c4a8b4/content/ppapi_plugin/ppapi_blink_platform_impl.h
[modify] https://crrev.com/017b79e68acccf53f361d80168cb85daa9c4a8b4/content/renderer/loader/web_url_loader_impl.cc
[modify] https://crrev.com/017b79e68acccf53f361d80168cb85daa9c4a8b4/content/renderer/loader/web_url_loader_impl.h
[modify] https://crrev.com/017b79e68acccf53f361d80168cb85daa9c4a8b4/content/renderer/render_frame_impl.cc
[modify] https://crrev.com/017b79e68acccf53f361d80168cb85daa9c4a8b4/content/renderer/render_frame_impl.h
[modify] https://crrev.com/017b79e68acccf53f361d80168cb85daa9c4a8b4/content/renderer/renderer_blink_platform_impl.cc
[modify] https://crrev.com/017b79e68acccf53f361d80168cb85daa9c4a8b4/content/renderer/renderer_blink_platform_impl.h
[modify] https://crrev.com/017b79e68acccf53f361d80168cb85daa9c4a8b4/content/renderer/service_worker/service_worker_fetch_context_impl.cc
[modify] https://crrev.com/017b79e68acccf53f361d80168cb85daa9c4a8b4/content/renderer/service_worker/service_worker_fetch_context_impl.h
[modify] https://crrev.com/017b79e68acccf53f361d80168cb85daa9c4a8b4/content/renderer/service_worker/worker_fetch_context_impl.cc
[modify] https://crrev.com/017b79e68acccf53f361d80168cb85daa9c4a8b4/content/renderer/service_worker/worker_fetch_context_impl.h
[modify] https://crrev.com/017b79e68acccf53f361d80168cb85daa9c4a8b4/content/test/test_blink_web_unit_test_support.cc
[modify] https://crrev.com/017b79e68acccf53f361d80168cb85daa9c4a8b4/content/test/test_blink_web_unit_test_support.h
[modify] https://crrev.com/017b79e68acccf53f361d80168cb85daa9c4a8b4/content/test/test_render_frame.cc
[modify] https://crrev.com/017b79e68acccf53f361d80168cb85daa9c4a8b4/content/test/test_render_frame.h
[modify] https://crrev.com/017b79e68acccf53f361d80168cb85daa9c4a8b4/third_party/WebKit/Source/core/exported/LocalFrameClientImpl.cpp
[modify] https://crrev.com/017b79e68acccf53f361d80168cb85daa9c4a8b4/third_party/WebKit/Source/core/exported/LocalFrameClientImpl.h
[modify] https://crrev.com/017b79e68acccf53f361d80168cb85daa9c4a8b4/third_party/WebKit/Source/core/exported/WorkerShadowPage.cpp
[modify] https://crrev.com/017b79e68acccf53f361d80168cb85daa9c4a8b4/third_party/WebKit/Source/core/exported/WorkerShadowPage.h
[modify] https://crrev.com/017b79e68acccf53f361d80168cb85daa9c4a8b4/third_party/WebKit/Source/core/frame/FrameTestHelpers.cpp
[modify] https://crrev.com/017b79e68acccf53f361d80168cb85daa9c4a8b4/third_party/WebKit/Source/core/frame/FrameTestHelpers.h
[modify] https://crrev.com/017b79e68acccf53f361d80168cb85daa9c4a8b4/third_party/WebKit/Source/core/frame/LocalFrame.cpp
[modify] https://crrev.com/017b79e68acccf53f361d80168cb85daa9c4a8b4/third_party/WebKit/Source/core/frame/LocalFrame.h
[modify] https://crrev.com/017b79e68acccf53f361d80168cb85daa9c4a8b4/third_party/WebKit/Source/core/frame/LocalFrameClient.h
[modify] https://crrev.com/017b79e68acccf53f361d80168cb85daa9c4a8b4/third_party/WebKit/Source/core/frame/WebLocalFrameImpl.cpp
[modify] https://crrev.com/017b79e68acccf53f361d80168cb85daa9c4a8b4/third_party/WebKit/Source/core/frame/WebLocalFrameImpl.h
[modify] https://crrev.com/017b79e68acccf53f361d80168cb85daa9c4a8b4/third_party/WebKit/Source/core/loader/EmptyClients.h
[modify] https://crrev.com/017b79e68acccf53f361d80168cb85daa9c4a8b4/third_party/WebKit/Source/core/loader/FrameFetchContext.cpp
[modify] https://crrev.com/017b79e68acccf53f361d80168cb85daa9c4a8b4/third_party/WebKit/Source/core/loader/WorkerFetchContext.cpp
[modify] https://crrev.com/017b79e68acccf53f361d80168cb85daa9c4a8b4/third_party/WebKit/Source/core/loader/WorkerFetchContext.h
[modify] https://crrev.com/017b79e68acccf53f361d80168cb85daa9c4a8b4/third_party/WebKit/Source/platform/loader/BUILD.gn
[modify] https://crrev.com/017b79e68acccf53f361d80168cb85daa9c4a8b4/third_party/WebKit/Source/platform/loader/testing/FetchTestingPlatformSupport.cpp
[modify] https://crrev.com/017b79e68acccf53f361d80168cb85daa9c4a8b4/third_party/WebKit/Source/platform/loader/testing/FetchTestingPlatformSupport.h
[modify] https://crrev.com/017b79e68acccf53f361d80168cb85daa9c4a8b4/third_party/WebKit/Source/platform/loader/testing/MockFetchContext.h
[add] https://crrev.com/017b79e68acccf53f361d80168cb85daa9c4a8b4/third_party/WebKit/Source/platform/loader/testing/WebURLLoaderFactoryWithMock.cpp
[add] https://crrev.com/017b79e68acccf53f361d80168cb85daa9c4a8b4/third_party/WebKit/Source/platform/loader/testing/WebURLLoaderFactoryWithMock.h
[modify] https://crrev.com/017b79e68acccf53f361d80168cb85daa9c4a8b4/third_party/WebKit/Source/platform/testing/TestingPlatformSupport.cpp
[modify] https://crrev.com/017b79e68acccf53f361d80168cb85daa9c4a8b4/third_party/WebKit/Source/platform/testing/TestingPlatformSupport.h
[modify] https://crrev.com/017b79e68acccf53f361d80168cb85daa9c4a8b4/third_party/WebKit/Source/platform/testing/URLTestHelpers.h
[modify] https://crrev.com/017b79e68acccf53f361d80168cb85daa9c4a8b4/third_party/WebKit/public/BUILD.gn
[modify] https://crrev.com/017b79e68acccf53f361d80168cb85daa9c4a8b4/third_party/WebKit/public/platform/Platform.h
[add] https://crrev.com/017b79e68acccf53f361d80168cb85daa9c4a8b4/third_party/WebKit/public/platform/WebURLLoaderFactory.h
[modify] https://crrev.com/017b79e68acccf53f361d80168cb85daa9c4a8b4/third_party/WebKit/public/platform/WebWorkerFetchContext.h
[modify] https://crrev.com/017b79e68acccf53f361d80168cb85daa9c4a8b4/third_party/WebKit/public/web/WebFrameClient.h
[modify] https://crrev.com/017b79e68acccf53f361d80168cb85daa9c4a8b4/third_party/WebKit/public/web/WebLocalFrame.h

 Issue 690400  has been merged into this issue.