Some cleanup to not pass both BrowserContext and IsolationContext.

This CL removes BrowserContext from BrowsingInstance, since it is
already stored in the BrowsingInstance's IsolationContext.  It also
removes BrowserContext from GetSiteForURL functions.

Future CLs will clean up other process model functions that take both
a BrowserContext and IsolationContext (such as
DoesSiteRequireDedicatedProcess) to only take IsolationContext.

Bug: 905513
Change-Id: Ibea91690930445a5c2d192476ad7180642dd2168
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1516098
Reviewed-by: Ɓukasz Anforowicz <[email protected]>
Commit-Queue: Alex Moshchuk <[email protected]>
Cr-Commit-Position: refs/heads/master@{#639678}
11 files changed