Intent to Enable Origin Trial support on Android WebView
Peter Birk Pakkenberg
Hello blink-dev@
We are hoping to begin rolling out origin trial support on WebView. The goal is to ensure that the origins who wish to test new Blink features can reach users in Android WebView as well.
Launch Bugs
http://crbug.com/1308425 (internal launch bug)
Summary
We will soon enable origin trials on Android WebView, which means that clients will start to honour Origin-Trial headers for trials that target the Android platform in runtime_enabled_features.json5, provided the feature is implemented for WebView. This means that a number of existing Blink trials will be enabled.
The long term goal is to achieve parity between WebView and Chrome on Android when it comes to experimentation for features implemented in Blink, which has two key benefits to the Chromium project. First, it provides a large number of additional clients to test new Blink features. Due to the embedded nature of WebView, this will provide new insights into a part of the web ecosystem that has previously not been accessible to experimentation (for example hybrid apps). In turn, this will help to avoid surprises for feature developers who rely on origin trials to launch new features, which will hopefully lead to smoother feature launches.
Why Now
Planned features on WebView require origin testing, making it a necessity to enable the framework. Additionally, the longer origin trials remain disabled on WebView, the more likely it is that a trial misses an issue on WebView that could have been found, like it has happened in the past.
Affected trials
By our analysis, 14 trials will be affected by the enablement on WebView. This means that they a) are targeting the Android platform, and b) have been implemented in shared code that is used by WebView. Other trials may rely on integrations in the embedder, which have not been implemented for WebView, which means that they won’t exhibit any new behaviour during the roll-out.
Rollout plan
WebView does not have good penetration on the dev/beta channels, so we will have to do the primary experiment on Stable. Given that we will be enabling all applicable origin trials on WebView at the same time as part of our feature roll-out, we expect full support to reach all WebView users in 3-4 weeks.
Feedback from the Blink community
We’d love to receive feedback and questions from the Blink community, either via this thread, in the launch bug or privately. Some of the things that we’ve been thinking about:
Should targeting Android in runtime_enabled_features.json5 include or exclude WebView? We propose for it to be included as the majority of trials are either applicable to WebView as well, or have the corresponding features disabled through other means in Chromium.
How should trial owners consider WebView metrics in their analysis? For Googlers, the UMA dashboards provide this ability, although WebView does not record UKM. Externally we’re investigating whether we can publish WebView metrics as part of chromestatus.com, but that’s adjacent to this effort.
How should Web developers consider WebView usage? For the trials that are applicable to WebView, ideally they wouldn’t. WebView powers a significant share of browsing time on Android, so in most cases this is an audience they already reach today, but (possibly unknowingly) isn’t covered by their own experimentation
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