Description(NOT FOR REVIEW) Distinguish between touch and touchmove handler presence
Currently, the renderer communicates a single bit about the presence
of touch handlers to the browser. This is used to avoid unnecessarily
sending touch events to the renderer when there are no appropriate
handlers.
However, it has been observed that a non-trivial number of sites add
touchstart handlers but no *touchmove* handlers. As dispatch of the
first touchmove to the renderer main thread can block scrolling, this
means we're unnecessarily blocking scrolling for sites that lack a
touchmove handler, increasing the risk of jank and scroll delay.
Instead, notify the WebWidgetClient when the existence of a particular
handler class has changed. This includes touch, touchmove, wheel and
scroll handlers. The embedder can then take the appropriate action to
optimize the non-existent touchmove handler case (as in
crrev.com/1050993004).
BUG=464721
Patch Set 1 #Patch Set 2 : Rebase #Patch Set 3 : rebase #Patch Set 4 : Rebase #Patch Set 5 : Fix loading #
Total comments: 1
Depends on Patchset: Messages
Total messages: 5 (1 generated)
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