Started in https://codereview.chromium.org/1972843002

status: chrome compiles \o/ with mac_views_browser = true 

(but, as I write this, not with = false - doh. Also lots of things need linting).

Thanks for getting started on this.

Since mac_views_browser isn't a shipped config at the moment, if you get the build working, I think you can make the GN version the definitive source of truth for mac_views_browser and stop supporting GYP.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/64351f1c48aebf9167b6b1a0cfcec6a1779fbffa

commit 64351f1c48aebf9167b6b1a0cfcec6a1779fbffa
Author: tapted <tapted@chromium.org>
Date: Tue May 17 06:10:50 2016

MacViews GN: Get chrome compiling with mac_views_browser = true

Three things only used by Mac+Cocoa (not mac_views_browser), but ignored
when linking with gyp since they were in the libbrowser.a library and
symbols in libbrowser_ui.a took precedence:
* Moves DownloadDangerPromptImpl from c/b/download to
c/b/ui/cocoa/download
* Moves chrome::ShowCreateChromeAppShortcutsDialog from
c/b/web_applications to c/b/ui/cocoa
* proximity_auth_error_bubble.cc had stubs only used by Cocoa.

Remove immersive_mode_controller_factory_mac.cc - Cocoa doesn't use it,
and mac_views_browser has an implementation in c/b/ui/views

gyp doesn't automatically strip _aura files -- move some aura-only stuff
into chrome_browser_ui_aura_sources. (x11_panel_resizer is Linux only
but was actually being compiled on all aura platforms - fix that).

chrome_browser_ui_views_*non_mac*_sources had some _mac stuff used by
mac_views_browser=1 builds, move these to
chrome_browser_ui_views_mac_experimental_sources to avoid confusion.

BUG= 611324 

Review-Url: https://codereview.chromium.org/1972843002
Cr-Commit-Position: refs/heads/master@{#394068}

[modify] https://crrev.com/64351f1c48aebf9167b6b1a0cfcec6a1779fbffa/chrome/browser/download/download_danger_prompt.cc
[modify] https://crrev.com/64351f1c48aebf9167b6b1a0cfcec6a1779fbffa/chrome/browser/ui/BUILD.gn
[add] https://crrev.com/64351f1c48aebf9167b6b1a0cfcec6a1779fbffa/chrome/browser/ui/cocoa/create_application_shortcut_cocoa.mm
[add] https://crrev.com/64351f1c48aebf9167b6b1a0cfcec6a1779fbffa/chrome/browser/ui/cocoa/download/download_danger_prompt_impl.cc
[rename] https://crrev.com/64351f1c48aebf9167b6b1a0cfcec6a1779fbffa/chrome/browser/ui/proximity_auth/proximity_auth_error_bubble_stub.cc
[delete] https://crrev.com/5e83219cd5e9db35e916cda86cf0e085316821cb/chrome/browser/ui/views/frame/immersive_mode_controller_factory_mac.cc
[modify] https://crrev.com/64351f1c48aebf9167b6b1a0cfcec6a1779fbffa/chrome/browser/web_applications/web_app_mac.mm
[modify] https://crrev.com/64351f1c48aebf9167b6b1a0cfcec6a1779fbffa/chrome/chrome_browser_ui.gypi

That gets `chrome` compiling. Other targets might need some TLC, but popping this off my runqueue for now.

And yeah, re #c2, go/macviewsbuilder might indeed be a good sandbox for switching to GN.. I guess there isn't a ton of gyp-specific stuff for mac_views_browser, but that might change if other views platforms turn down gyp before we do on mac.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/63a7fcd115f12a5f955014ab805cae1a6934c432

commit 63a7fcd115f12a5f955014ab805cae1a6934c432
Author: rsesek <rsesek@chromium.org>
Date: Wed Jun 15 16:03:20 2016

[Mac/GN] Remove views_test_suite.cc from macviews_interactive_ui_tests sources.

It is already part of //ui/views:test_support, which is a dependency.

BUG= 619781 , 611324 
TBR=sky@chromium.org

Review-Url: https://codereview.chromium.org/2056313003
Cr-Commit-Position: refs/heads/master@{#399910}

[modify] https://crrev.com/63a7fcd115f12a5f955014ab805cae1a6934c432/ui/views/BUILD.gn

As suggested by laforge@ and a conversation w/ the monorail folks, I'm going to try tracking GN-Migration related issues by *just* using the Proj-GN-Migration label, and not using blocking/rollup bugs, so that we can use blocking for just tasks that truly need to be completed before other tasks can make progress.

d3b350b39b0f2f79881778f6c026ad7dd6c12432  flipped the MacVIews 10.10 bot and it passes compile: https://build.chromium.org/p/chromium.fyi/builders/Chromium%20Mac%2010.10%20MacViews/builds/11916