The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/4940aa0a3252a388c248026706f9f8f06abe7767

commit 4940aa0a3252a388c248026706f9f8f06abe7767
Author: Peter Boström <pbos@chromium.org>
Date: Thu Nov 08 22:20:05 2018

Respect theme colors for new tab-loading animation

Uses 12% opacity of white / black for the placeholder depending on contrast
instead of hard-coding GoogleBlue100. For the bouncing pill, use theme colors
previously used for the spinner.

Bug:  chromium:903457 
Change-Id: I6dd46ac516a8fef874ecdf95bcaef3b57d7a5974
Reviewed-on: https://chromium-review.googlesource.com/c/1327422
Reviewed-by: Elly Fong-Jones <ellyjones@chromium.org>
Commit-Queue: Peter Boström <pbos@chromium.org>
Cr-Commit-Position: refs/heads/master@{#606620}
[modify] https://crrev.com/4940aa0a3252a388c248026706f9f8f06abe7767/chrome/browser/ui/views/tabs/tab.cc
[modify] https://crrev.com/4940aa0a3252a388c248026706f9f8f06abe7767/chrome/browser/ui/views/tabs/tab_icon.cc
[modify] https://crrev.com/4940aa0a3252a388c248026706f9f8f06abe7767/chrome/browser/ui/views/tabs/tab_icon.h

The new colours have landed. Unexpectedly the connecting pill uses a grey. Seems like the connecting state uses another theme colour and not the blue as was assumed. 

Deleted: grey-connecting-state.gif 20.9 KB

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The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/ce58bfa0bccae56fffff5e79aecab69960afcd88

commit ce58bfa0bccae56fffff5e79aecab69960afcd88
Author: Peter Boström <pbos@chromium.org>
Date: Mon Nov 12 17:03:36 2018

Use blue for both throbber and loading animation

This makes use of COLOR_TAB_THROBBER_SPINNING in both the loading and
waiting states.

Bug:  chromium:903457 
Change-Id: I3e6bed8392c956604649c42eb8fcef1d10a7a8c9
Reviewed-on: https://chromium-review.googlesource.com/c/1329349
Reviewed-by: Elly Fong-Jones <ellyjones@chromium.org>
Commit-Queue: Peter Boström <pbos@chromium.org>
Cr-Commit-Position: refs/heads/master@{#607270}
[modify] https://crrev.com/ce58bfa0bccae56fffff5e79aecab69960afcd88/chrome/browser/ui/views/tabs/tab_icon.cc

Please consider cleaning up the enum values and names to reflect what we actually do now...

Intending to do this once we don't have the experiment anymore.

Tried testing the issue on chrome version #72.0.3606.0 and latest chrome #72.0.3610.0 using windows 10, below are the observations noted while testing the issue.

Observations:
===========
1.In both the chrome versions (#72.0.3606.0 and #72.0.3610.0), while opening a new tab in incognito the loading animation is in white color but not gray and blue respectively.
2.In normal tab on chrome version #72.0.3606.0 the loading animation is gray in the start on progess it turns blue and on chrome version #72.0.3610.0 the loading animation is blue from very first start.
Attached screencasts for reference.

@Peter Boström: Could you please confirm that the fix is intended is only for normal tab or both normal tab and incognito, so that it would be really helpful in verifying the fix.
Thanks.!

Deleted: 903457_(72.0.3606.0).mp4 5.3 MB

	903457_(72.0.3606.0).mp4 5.3 MB View Download

Deleted: 903457_(72.0.3610.0).mp4 4.9 MB

	903457_(72.0.3610.0).mp4 4.9 MB View Download

"blue from very first start" WAI, in incognito this should be grey throughout both animation states.