Do not send redundant selectionchange-events (decouple focus)
This CL aims to remove redundant selectionchange-events
that were sent upon change of focus caused by element.focus(),
tab-navigation, spatnav and mouse-clicks.
Goals:
1. Send == one selectionchange-event, not two, for each caret jump.
2. Send <= one selectionchange-event, not two, for each focus jump.
Background:
When you click/tab to an <input> text-field, a
ViewHostMsg_TextInputStateChanged-message is sent to browser-side.
Problem:
With current logic, RenderFrameImpl::didChangeSelection is
called twice so two ViewHostMsg_TextInputStateChanged-messages
are sent to browser-side:
(1) when focus leaves an <input>-field (unnecessary!).
(2) when focus enters another <input>-field.
Worse, also the web page gets two selectionchange events.
The first one is immediately invalid so the webpage should
not react to it.
(1) happens because FocusController::setFocusedElement()
always clears the selection when a new element gets focus.
Solution:
Do not clear selection when focus moves. To keep current visual
behavior when focus moves away from a text-field we need to hide
that field's selection (clicking outside a text-field hides its
selection).
Test updates:
1. Check for one selectionchange event, not two.
2. LayoutTests' trees now expect the "hidden" selection.
3. A new test in WebFrameTest.cpp tests tab-key navigation.
BUG=678601, 679635, 699015, 692898
TEST=In content_shell, select some text in an <input>-field,
click another <input>-field (move focus).
Notice: one selectionchange event is fired (as in Firefox).
TEST=In content_shell, select some text in an <input>-field,
click on an <img>. Notice: selection gets hid and
zero selectionchange events are fired (as in Firefox).
Review-Url: https://codereview.chromium.org/2616623002
Cr-Commit-Position: refs/heads/master@{#464698}
22 files changed
