1193454 - [e10s] On TabChild::RecvActivate, IMEStateManager can send a sync message to the parent process

Status: RESOLVED WONTFIX

(Core :: DOM: UI Events & Focus Handling, defect)

Description

[Mike Conley (:mconley) (:⚙️)]

See http://people.mozilla.org/~bgirard/cleopatra/#report=5495de8a52fd98e4b83c02135d49183edecbaddd&filter=[{%22type%22%3A%22RangeSampleFilter%22,%22start%22%3A6792279,%22end%22%3A6792421}]&selection=0,39,40,1589,1590,1591,1592,51,52,1593,1594,49,50,51,52,1593,53,54,227,228,229,230,231,232,1622,1876,1624,1877,1878,1879

I gathered that while switching tabs on Windows. I'm seeing this stack in here:

mozilla::dom::TabChild::RecvActivate
nsWebBrowser::Activate
nsFocusManager::WindowRaised
nsFocusManager::Focus
mozilla::IMEStateManager::OnChangeFocusInternal
mozilla::IMEStateManager::SetIMEState
mozilla::widget::PuppetWidget::GetInputContext
IPDL::PBrowser::SendGetInputContext
mozilla::dom::PBrowserChild::SendGetInputContext <-- sync message

So we're sending a sync message to the parent at least in some cases when switching tabs, and I'm not even using IME.

Hey masayuki - if this input context information is necessary here, do you know if it's possible for us to send it down in the Activate message send down from TabParent to avoid this sync message?

Comment 1

[Masayuki Nakano [:masayuki] (he/him)(JST, +0900)]

It's necessary and needs to be sync since it retrieves the current input context.

And setting input context is necessary even if you don't use IME actually. It controls setting input scope for VKB state, enabling/disabling secure input, etc.

Comment 2

[Mike Conley (:mconley) (:⚙️)]

Alright, thanks for laying that out masayuki.