Navigator.Plugins() and Navigator.MimeTypes() will only report the presence of Flash Player if the user has indicated that the domain should execute Flash.
HTML5 by default has shipped and we are currently in the process of ramping up the SEI threshold, per the schedule below.
Currently 87.5% of population have an SEI threshold score of 4 and 12.5% has a threshold score of 8 (we do this to measure the impact of the threshold change). By the end of the month we will progress on to the next phase on the ramp and everyone will be at least at 8.
HTML5 by Default was initially rolled out to 1% of Chrome 55 Stable users (December), followed by a full deployment (i.e. to 100% of users) in Chrome 56 Stable (February).
Flash prompting will only be enabled for sites whose Site Engagement Index (SEI) is below a certain threshold. For Chrome 55, starting in January 2017 prompts will only appear for sites where the user’s SEI is less than 1. That threshold will increase to 100 through October 2017, when all Flash sites will require an initial prompt. As a reminder, users will only be prompted once per site.
Here’s a summary of thresholds and % of users:
Ultimately we recommend migrating towards HTML5 content, however for sites that still require Flash Player in the interim we recommend presenting users with either one of the following enablement options:
We are removing the final exception for Plugin Power Savings Mode, which permitted small (5x5) content, hosted on the same origin, to run.
The exception was meant to be a temporary relief for smaller developers, for features that are well now very supported by the web platform (e.g. clipboard access, audio streams, etc...).
Reduce the number of Flash Player modes from 3 options (Always Allow, Ask, Block) to 2 (a single toggle for Ask or Block).
The intent is to simplify the user choice down to a single option, enable Flash Player (default == enabled), that is easy for users to understand. Power users will be able to add exceptions (including those with wildcards) explicitly Allow Flash to run.
Click to Play will be enabled for all Flash Player instances, even on sites where Flash Player is allowed to run per HTML5 by Default.
Require affirmative user choice to run Flash Player content, without that choice persisting across multiple sessions.
Chrome pauses non-essential(1) Flash Content, by replacing the plugin content with a static image preview and a play button overlayed. Users can re-enable this content by clicking play.
(1) - Non-essential content being smaller than 300x400 pixels or smaller than 5x5 pixels.
Limit Flash Playbacks to visible main body content (e.g. video, games, etc...) and still permit streaming audio services to function.
A further restriction to Plugin Power Savings Mode that removes the ability to run 5x5 or smaller content, from a different origin.
Much of this content (5x5 below) was used for viewability detection (i.e. to see if an ad was on that page), requiring Chrome to spin up a relatively expensive (in terms of performance) Flash process in order for the site to infer viewability.
With the introduction of Intersection Observer in Chrome 51, which added platform support for this use case, there was no longer a need to continue granting this exception.
We left an exception for "same origin" 5x5 Flash content, to give smaller sites (e.g. using things like clipboard access) time to migrate.
Chrome to automatically use the HTML5 content of a YouTube embed when the Flash one is used.
This will allow the long tail of websites that never updated to the HTML5 embeds to no longer require Flash for Chrome users, thus reducing overall usage of Flash in Chrome.
Chrome to exclusively use the component updater to distribute Flash Player, and separating it from Chrome's default distribution bundle.
Enable Chrome to rapidly distribute Flash Player updates, without re-building the core product, making it easier to match Adobe's monthly release cadence.
This feature was fundamentally technology gated, requiring development of in-line on-demand Flash component installs, differential component updates, and building out special serving infrastructure.