Also, make the same change to nsPresContext::GetTextInputHandlingWidget and
TextComposition::GetWidget, which are essentially aliases/wrappers for this
function.
This patch shouldn't change behavior at all, aside from:
* optimizing away some redundant reference counting and widget-lookups
* delaying some nsIWidget::Release() calls, which will now happen after we're
actually done using the object, instead of happening when the getter
completes. (It's unlikely this impacts behavior, because there are other
objects that are keeping the nsIWidget instance alive.)
Motivation / "wins" from this patch:
* nsPresContext::GetRootWidget already works with a refcounted pointer
internally. Before this patch, it drops the reference before returning the
pointer. This is a bit suspect and would cause security issues, in the
unlikely event that this were the last strong reference to the object. It
can just as easily/efficiently transfer the strong reference to the caller,
and let the caller determine when to release it.
* Many of the callers were already storing the return value in nsCOMPtr, which
meant that they were incurring an additional AddRef/Release when
populating/destructing that smart pointer. Now they can just take ownership
of the already_AddRefed return value and avoid redundnat refcount-churn.
* For the callers that weren't storing the return value in nsCOMPtr, some of
them were calling this getter twice in a row (once to test for truthiness and
once to use the known-truthy value). This was wasteful, both from the
repeated lookup-work (since the function isn't a trivial getter), and from
repeated refcount-churn. This patch collapses these repeat-calls to a single
call, avoiding those inefficiencies.
Differential Revision: https://phabricator.services.mozilla.com/D127180
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https://firefox-source-docs.mozilla.org/contributing/contribution_quickref.html
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https://www.mozilla.org/firefox/channel/desktop/#nightly
Keep in mind that nightly builds, which are used by Firefox developers for
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