Chrome Version: 72.0.3590.0
OS: Android

On Android, the outer (layout) viewport is sized using the minimum-page-scale which depends on the content-size. This originates in WebViewImpl::ResizeAfterLayout.

On a page like https://ritzy-green.glitch.me/ (attached for reference), the content is 320 pixels, so on a device with a larger screen, the content is laid out into 320 pixels of width. This means the minimum-scale is > 1 so the page loads zoomed in and the layout viewport is less wide than the device screen.

The resize-after-layout affects both the FrameView and the LayoutView size so I would expect the ClipNode belonging to the outer viewport to also have the resize applied but it doesn't - it's the same size as the visual viewport's clip. This is the root cause of  bug 898757 . That bug needs a mergeable fix so this bug tracks fixing the root cause.

The clip is correctly calculated with --enable-blink-gen-property-trees so perhaps just letting that ship is enough.
 

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