[SimpleCache] Track some SimpleCache size stats on initialization

net/disk_cache/simple/simple_index.cc

 // Copyright (c) 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 "net/disk_cache/simple/simple_index.h"
 
 #include <algorithm>
 #include <limits>
 #include <string>
 #include <utility>
@@ skipping 423 matching lines @@
   init_method_ = load_result->init_method;
 
   // The actual IO is asynchronous, so calling WriteToDisk() shouldn't slow the
   // merge down much.
   if (load_result->flush_required)
     WriteToDisk(INDEX_WRITE_REASON_STARTUP_MERGE);
 
   SIMPLE_CACHE_UMA(CUSTOM_COUNTS,
                    "IndexInitializationWaiters", cache_type_,
                    to_run_when_initialized_.size(), 0, 100, 20);
+  SIMPLE_CACHE_UMA(CUSTOM_COUNTS, "IndexNumEntriesOnInit", cache_type_,
+                   entries_set_.size(), 0, 100000, 50);
+  SIMPLE_CACHE_UMA(
+      MEMORY_KB, "CacheSizeOnInit", cache_type_,
+      static_cast<base::HistogramBase::Sample>(cache_size_ / kBytesInKb));
+  SIMPLE_CACHE_UMA(
+      MEMORY_KB, "MaxCacheSizeOnInit", cache_type_,
+      static_cast<base::HistogramBase::Sample>(max_size_ / kBytesInKb));
+  if (max_size_ > 0) {
+    SIMPLE_CACHE_UMA(PERCENTAGE, "PercentFullOnInit", cache_type_,
+                     static_cast<base::HistogramBase::Sample>(
+                         (cache_size_ * 100) / max_size_));
+  }
+
   // Run all callbacks waiting for the index to come up.
   for (CallbackList::iterator it = to_run_when_initialized_.begin(),
        end = to_run_when_initialized_.end(); it != end; ++it) {
     io_thread_->PostTask(FROM_HERE, base::Bind((*it), net::OK));
   }
   to_run_when_initialized_.clear();
 }
 
 #if defined(OS_ANDROID)
 void SimpleIndex::OnApplicationStateChange(
@@ skipping 30 matching lines @@
                        start - last_write_to_disk_);
     }
   }
   last_write_to_disk_ = start;
 
   index_file_->WriteToDisk(reason, entries_set_, cache_size_, start,
                            app_on_background_, base::Closure());
 }
 
 }  // namespace disk_cache