Reset some UMA stability stats on a version change.

chrome/browser/metrics/plugin_metrics_provider.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 "chrome/browser/metrics/plugin_metrics_provider.h"
 
 #include <string>
 
 #include "base/prefs/pref_registry_simple.h"
 #include "base/prefs/pref_service.h"
@@ skipping 178 matching lines @@
     int loading_errors = 0;
     plugin_dict->GetInteger(prefs::kStabilityPluginLoadingErrors,
                             &loading_errors);
     if (loading_errors > 0)
       plugin_stability->set_loading_error_count(loading_errors);
   }
 
   local_state_->ClearPref(prefs::kStabilityPluginStats);
 }
 
+void PluginMetricsProvider::ClearSavedStabilityMetrics() {
+  local_state_->ClearPref(prefs::kStabilityPluginStats);
+}
+
 // Saves plugin-related updates from the in-object buffer to Local State
 // for retrieval next time we send a Profile log (generally next launch).
 void PluginMetricsProvider::RecordCurrentState() {
   ListPrefUpdate update(local_state_, prefs::kStabilityPluginStats);
   base::ListValue* plugins = update.Get();
   DCHECK(plugins);
 
   for (base::ListValue::iterator value_iter = plugins->begin();
        value_iter != plugins->end(); ++value_iter) {
     if (!(*value_iter)->IsType(base::Value::TYPE_DICTIONARY)) {
@@ skipping 164 matching lines @@
 }
 
 bool PluginMetricsProvider::RecordCurrentStateIfPending() {
   if (!weak_ptr_factory_.HasWeakPtrs())
     return false;
 
   weak_ptr_factory_.InvalidateWeakPtrs();
   RecordCurrentState();
   return true;
 }