Add Precache.Fetch.ResponseBytes.Daily.

components/precache/core/precache_fetcher.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "components/precache/core/precache_fetcher.h"
 
 #include <algorithm>
 #include <limits>
 #include <set>
 #include <utility>
@@ skipping 700 matching lines @@
   PostTaskAndReplyWithResult(
       db_task_runner_.get(), FROM_HERE,
       base::Bind(&RetrieveQuotaInfo, precache_database_),
       base::Bind(&PrecacheFetcher::OnQuotaInfoRetrieved, AsWeakPtr()));
 }
 
 void PrecacheFetcher::OnQuotaInfoRetrieved(const PrecacheQuota& quota) {
   quota_ = quota;
   base::Time time_now = base::Time::Now();
   if (IsQuotaTimeExpired(quota_, time_now)) {
+    UMA_HISTOGRAM_CUSTOM_COUNTS(
+        "Precache.Fetch.ResponseBytes.Daily",
+        unfinished_work_->config_settings().daily_quota_total() -
+            quota_.remaining(),

[jamartin, 2017/03/07 21:10:12]

(opt) It would be nice to have a bit more documentation in the Quota proto. It
took me a while to figure out the meaning of the fields and how they were
supposed to be used.

[twifkak, 2017/03/07 21:45:09]

Done.

+        1, kMaxResponseBytes, 100);

[jamartin, 2017/03/07 21:10:12]

I assume you eyeballed the bucket values and they make sense for this case,
right?

[twifkak, 2017/03/07 21:45:09]

Yes. The max is 500MB, which is more than enough for the 40MB/day we allot. The
bucket config is the same as the other ResponseBytes histos, and provide enough
detail for those (which sit around the 10MB range).

+
     // This is a new day. Update daily quota, that starts today and expires by
     // end of today.

[jamartin, 2017/03/07 21:10:12]

Keep the comment at the beginning of the if block.

[twifkak, 2017/03/07 21:45:09]

Done.

     quota_.set_start_time(time_now.LocalMidnight().ToInternalValue());
     quota_.set_remaining(
         unfinished_work_->config_settings().daily_quota_total());
     db_task_runner_->PostTask(
         FROM_HERE,
         base::Bind(&PrecacheDatabase::SaveQuota, precache_database_, quota_));
   }
   StartNextFetch();
 }
 
@@ skipping 149 matching lines @@
       remaining = 0;
     quota_.set_remaining(
         used_bytes > quota_.remaining() ? 0U : quota_.remaining() - used_bytes);
     db_task_runner_->PostTask(
         FROM_HERE,
         base::Bind(&PrecacheDatabase::SaveQuota, precache_database_, quota_));
   }
 }
 
 }  // namespace precache