CacheStorage: Fix typos in histograms.xml after last update.

This CL corrects some typoes added in in crrev.com/c/1468144:

1. The ServiceWorkerCache.Cache.*.Match histogram contains its
   own values in addition to have child suffixes.  It should not be
   marked as a pure base.
2. The ServiceWorkerCache.CacheStorage operation suffixes were applied
   to the ServiceWorkerCache.Cache.* histograms incorrectly.

Bug: 927537
Change-Id: I3d46f1aca0b6d7f90ee14a8b18694cfeb5b0f51a
Reviewed-on: https://chromium-review.googlesource.com/c/1481470Reviewed-by: Robert Kaplow <rkaplow@chromium.org>
Commit-Queue: Ben Kelly <wanderview@chromium.org>
Cr-Commit-Position: refs/heads/master@{#634742}

tools/metrics/histograms/histograms.xml

@@ -144672,7 +144672,7 @@ uploading your change for review.
       label="The time to perform the 'keys' operation on a given Cache. This
              includes measurements for both invocations targeting all entries
              or only entries for a specific request parameter."/>
-  <suffix base="true" name="Match"
+  <suffix name="Match"
       label="The time to perform a 'match' operation on a given Cache. This
              includes measurements for all invocations, including hits,
              misses, errors, etc."/>
@@ -144789,8 +144789,8 @@ uploading your change for review.
              opening operations may happen asynchronously after the 'open'
              returns a Cache object. That deferred asynchronous work is not
              included in this measurement."/>
-  <affected-histogram name="ServiceWorkerCache.Cache.Browser"/>
-  <affected-histogram name="ServiceWorkerCache.Cache.Renderer"/>
+  <affected-histogram name="ServiceWorkerCache.CacheStorage.Browser"/>
+  <affected-histogram name="ServiceWorkerCache.CacheStorage.Renderer"/>
 </histogram_suffixes>
 
 <histogram_suffixes name="ServiceWorkerCache.ProcessSuffixes" separator=".">