Current Behavior:
For non-WebAPKs, the splash screen icon is downsampled to 128dp in ManifestIconDownloader::OnIconFetched().
For WebAPKs, the server ignores icons with size greater than 1MB

Proposal:
When the WebAPK Minting server generates a WebAPK, the generated WebAPK must be compatible with all screen densities. Thus, the maximum icon size needs to be enforced on the client, not the server.
I suggest introducing a new splash screen layout: webapp_splash_screen_super_large.xml The new layout would be used whenever the splash screen icon is larger than 128x128dp and would scale the icon down to 128x128dp

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/f97e28e3d46daa0d399a42ff535b7ad84897bc71

commit f97e28e3d46daa0d399a42ff535b7ad84897bc71
Author: Peter Kotwicz <pkotwicz@chromium.org>
Date: Fri Aug 31 21:39:08 2018

[Android WebAPK]: Downsample WebAPK splash screen icon if it is super big

This CL changes the behavior of the splash icon for WebAPKs to match that of
non-WebAPK homescreen shortcuts. The splash icon for
non-WebAPK-homescreen-shortcuts is downsampled to 128x128dp by
ManifestIconDownloader::OnIconFetched()

The WebAPK Minting server generates a single WebAPK per start URL. That single
WebAPK needs to work with all screen densities, thus the downsampling needs to
occur on the client side.

BUG= 879255 

Change-Id: I5822e1c8bf3cf02d7d3935989ae4d786cc9d9bb8
Reviewed-on: https://chromium-review.googlesource.com/1197623
Reviewed-by: Yaron Friedman <yfriedman@chromium.org>
Reviewed-by: Ted Choc <tedchoc@chromium.org>
Commit-Queue: Peter Kotwicz <pkotwicz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#588176}
[modify] https://crrev.com/f97e28e3d46daa0d399a42ff535b7ad84897bc71/chrome/android/java/res/layout/webapp_splash_screen_large.xml