O Google has started testing a new form of voice search for smartphones in the Chrome browser for Android. The intention is, of course, to facilitate voice search, but not only that. The desire to implement the change arose to also facilitate access to the Google Assistant interface.
According to XDA Developers, the idea, developed at the beginning of the year but only now put into testing (for now only in Chrome Canary, the preview used for developers), is to fix the microphone button at the top of Chrome used on smartphones (highlighted in the photo below).

How to trigger voice search in Chrome for Android
Before the new feature was discovered by XDA Developers, there were already other ways to activate voice search in Chrome to Android, such as pressing and holding the home button or using the OK Google voice command.
To enable the microphone button, the user must, in addition to having the latest version of Chrome, enable the following flags in chrome :/ / flags: Omnibox Assistant Voice Search and Voice button in top toolbar. The latter appears with the description “enable the appearance of the voice search button at the top of the toolbar”.
Once this is done, the user will need to disable the Share Button in top toolbar flag. Only then will the voice search button appear fixed in Chrome for Android on smartphones that are already released for testing the feature.
Voice search button may not reach all users
Not all Chrome users on Android smartphones will have the opportunity to test the new voice search button, according to information gathered on the Chromium Gerrit forum.
According to the most recent discussions, developers are still working on implementing the feature and, as has happened in other tests, the idea of definitively implementing the system in Chrome for Android may not come to fruition.
Street: XDA Developers