Add parser for new cpu freq file

chrome/browser/ui/webui/chromeos/power_ui.cc

Index: chrome/browser/ui/webui/chromeos/power_ui.cc
diff --git a/chrome/browser/ui/webui/chromeos/power_ui.cc b/chrome/browser/ui/webui/chromeos/power_ui.cc
index 0a354f96a47efe4e8eae8c851e5080d16553a6d2..b593b0277e218ec9ff4df9794ea08235793f6724 100644
--- a/chrome/browser/ui/webui/chromeos/power_ui.cc
+++ b/chrome/browser/ui/webui/chromeos/power_ui.cc
@@ -176,7 +176,7 @@ void PowerMessageHandler::GetJsStateOccupancyData(
           new base::DictionaryValue);
       for (size_t index = 0; index < sample.time_in_state.size(); ++index) {
         state_dict->SetDouble(state_names[index],
-                              static_cast<double>(sample.time_in_state[index]));
+                              sample.time_in_state[index].InMillisecondsF());
       }
       js_sample->Set("timeInState", std::move(state_dict));