Bug 227393

Summary:	ResourceTiming `transferSize` implementation should expose revalidation state
Product:	WebKit	Reporter:	Yoav Weiss <yoav>
Component:	Platform	Assignee:	Nobody <webkit-unassigned>
Status:	NEW ---
Severity:	Normal	CC:	achristensen, webkit-bug-importer
Priority:	P2	Keywords:	InRadar
Version:	WebKit Nightly Build
Hardware:	Unspecified
OS:	Unspecified

Description Yoav Weiss 2021-06-25 03:04:56 PDT

As discussed on the WebPerf WG call [1], the experimental `transferSize` implementation [2] should align to the spec [3] and well as the outstanding relevant PR [4], and expose:
* The encodedBodySize + 300 for resources that were fetched over the network
* 0 for resources that were fetched from the cache
* 300 for resources that were successfully revalidated over the network, and their body was then delivered from cache.

[1] https://docs.google.com/document/d/10dz_7QM5XCNsGeI63R864lF9gFqlqQD37B4q8Q46LMM/edit?pli=1#heading=h.gkilfdieaqp
[2] https://github.com/WebKit/WebKit/blob/b5cd1015460639460f55ae4b05bc90ff4ea5125e/Source/WebCore/page/PerformanceResourceTiming.cpp#L246
[3] https://w3c.github.io/resource-timing/#dom-performanceresourcetiming-transfersize
[4] https://github.com/w3c/resource-timing/pull/272

Comment 1 Radar WebKit Bug Importer 2021-07-02 03:05:18 PDT

<rdar://problem/80074642>