audit: Can prompt recurring visitor to install to homescreen about lighthouse HOT 12 CLOSED

from the docs: "Your icon declarations should include a mime type of image/png"

@brendankenny is going to verify in the source

https://code.google.com/p/chromium/codesearch#chromium/src/chrome/browser/banners/app_banner_data_fetcher.cc&q=%22bool%20AppBannerDataFetcher::IsManifestValidForWebApp%22&sq=package:chromium&type=cs

also found in //src/chrome/android/java/res/values/dimens.xml:

 <dimen name="webapp_home_screen_icon_size">48dp</dimen>

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currently required in manifest:

• valid start_url
• valid name
• valid short_name
• icon of size >= 144x144 and png (either type image/png or filename ending in .png)

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"valid". for url it's valid by chromium's gURL standards, right? and then the two names it checks for exists and not empty?

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for valid URL, it does appear that's correct. For the name checks, you may technically be able to get away with empty strings (it checks they aren't null), but I'm not sure. The manifest parse step may just covert empty strings to null.

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Nearly done, but we need to check for 144px icons instead of 192px. (But having 192 icons would allow the test to pass)

brendan said:

. The change shouldn't be long in the icons-192 audit. Split on 'x' (which is required to be lowercase after parsing), parseInt on each, then check that both width and height are >= 144

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@brendan i have this alsmost complete in a branch on my fork. 1% battery. see you guys.

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To add to this, on a macbook pro, I get a "256px square icon is required" in Chrome. The 256px appears to come from it not taking the emulated screen into account, but we may need to investigate the "square" part of that.

This seems to discard non-square icons:
https://code.google.com/p/chromium/codesearch#chromium/src/chrome/browser/manifest/manifest_icon_selector.cc&rcl=1459883706&l=43

but this explicitly tests non-square as OK:
https://code.google.com/p/chromium/codesearch#chromium/src/chrome/browser/banners/app_banner_data_fetcher_unittest.cc&sq=package:chromium&type=cs&q=%22Non-square%20is%20okay%22%20file:%5Esrc/chrome/browser/banners/

so not sure how these two worlds interact within Chrome.

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Fixed by the icons PR: #116

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Just verifying the check here:

source: https://cs.chromium.org/chromium/src/chrome/browser/installable/installable_manager.cc?type=cs&q=IsManifestValidForWebApp&sq=package:chromium&l=304

validity requires ALL of these:

1. manifest is not empty
2. manifest has valid start url
3. manifest has a valid name and valid shortname
4. manifest display property is either standalone or fullscreen
5. manifest contains icon that's a png and size >= 144px
6. SW is registered, and it owns this page and the manifest's start url
7. Site engagement score of 2 or higher

Our audit is a little softer in its tests so far. It doesn't look at standalone/fullscreen and doesn't consider SW controlling the starturl. Also it checks for shortname || name when it should be shortname && name. Also obviously we don't look at site engagement.

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manifest has a valid name and valid shortname

this one has been confusing because of the difference in context of use of the short_name. See #348, for instance. We should add a clear comment on this when we fix this :)

It doesn't look at standalone/fullscreen

IMO we should get rid of the manifest display audit and rename it chrome-a2hs-display.js or whatever to make it clear what it is and test only for standalone/fullscreen

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Looked again at the current implementation (installable_manager.cc and app_banner_manager.cc):

1. is secure
   • is either localhost or has a valid SSL Certificate
2. has a service worker
   • it must control the current url and the manifest's start_url
3. valid_manifest
   • has a valid starturl
   • has either a name or shortname (that isn't an empty string)
   • display is standalone/fullscreen/minimal-ui
4. has a satisfactory icon
   • must be a png
   • must be square
   • must be at least 72px, but chrome much prefers 144px or larger.
5. has sufficient engagement
   • currently requires a 2. see at chrome://site-engagement/

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k cool​

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