[UMA, Cleanup] Deprecate the UMA.GeneratedLowEntropySource histogram.

components/metrics/metrics_state_manager.cc

 // Copyright 2014 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/metrics/metrics_state_manager.h"
 
 #include "base/command_line.h"
 #include "base/guid.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/metrics/sparse_histogram.h"
@@ skipping 230 matching lines @@
   }
 
   // The GUID retrieved (and possibly fixed above) should be valid unless
   // retrieval failed.
   DCHECK(!client_info || base::IsValidGUID(client_info->client_id));
 
   return client_info.Pass();
 }
 
 int MetricsStateManager::GetLowEntropySource() {
+  UpdateLowEntropySource();
+  return low_entropy_source_;
+}
+
+void MetricsStateManager::UpdateLowEntropySource() {
   // Note that the default value for the low entropy source and the default pref
   // value are both kLowEntropySourceNotSet, which is used to identify if the
   // value has been set or not.
   if (low_entropy_source_ != kLowEntropySourceNotSet)
-    return low_entropy_source_;
+    return;
 
   const base::CommandLine* command_line(base::CommandLine::ForCurrentProcess());
   // Only try to load the value from prefs if the user did not request a
   // reset.
   // Otherwise, skip to generating a new value.
   if (!command_line->HasSwitch(switches::kResetVariationState)) {
     int value = local_state_->GetInteger(prefs::kMetricsLowEntropySource);
     // If the value is outside the [0, kMaxLowEntropySize) range, re-generate
     // it below.
     if (value >= 0 && value < kMaxLowEntropySize) {
       low_entropy_source_ = value;
-      UMA_HISTOGRAM_BOOLEAN("UMA.GeneratedLowEntropySource", false);
-      return low_entropy_source_;
+      return;
     }
   }
 
-  UMA_HISTOGRAM_BOOLEAN("UMA.GeneratedLowEntropySource", true);
   low_entropy_source_ = GenerateLowEntropySource();
   local_state_->SetInteger(prefs::kMetricsLowEntropySource,
                            low_entropy_source_);
   CachingPermutedEntropyProvider::ClearCache(local_state_);
-
-  return low_entropy_source_;
 }
 
 void MetricsStateManager::UpdateEntropySourceReturnedValue(
     EntropySourceType type) {
   if (entropy_source_returned_ != ENTROPY_SOURCE_NONE)
     return;
 
   entropy_source_returned_ = type;
   UMA_HISTOGRAM_ENUMERATION("UMA.EntropySourceType", type,
                             ENTROPY_SOURCE_ENUM_SIZE);
@@ skipping 10 matching lines @@
 
   local_state_->ClearPref(prefs::kMetricsClientID);
   local_state_->ClearPref(prefs::kMetricsLowEntropySource);
   local_state_->ClearPref(prefs::kMetricsResetIds);
 
   // Also clear the backed up client info.
   store_client_info_.Run(ClientInfo());
 }
 
 }  // namespace metrics