CacheStorage: Always complete mojo operations through the same callback.

Currently the CacheStorageDispatchingHost mojo implementations can invoke
their callbacks via different code paths.  For example, if the
CacheStorageHandle has been invalidated then the mojo callback is called
directly.  In contrast, if the underlying operation was actually performed
then a separate callback is first executed before calling the mojo callback.

This CL makes all cases go through the intermediate callback before invoking
the mojo callback.  This gives us a common place to put histogram measurement
and tracing code.

Bug: 927537
Change-Id: Ic1f1fd6107566c64b653628121f136315b589cab
Reviewed-on: https://chromium-review.googlesource.com/c/1474110
Reviewed-by: Daniel Murphy <dmurph@chromium.org>
Commit-Queue: Ben Kelly <wanderview@chromium.org>
Cr-Commit-Position: refs/heads/master@{#632898}
1 file changed