[CodeHealth] Remove uses of ListValue::begin()/end() in /dbus.

This CL removes calls to these deprecated member functions. It also
converts to the newer "for" loop syntax when possible, along with
other minor cleanup.

This CL was uploaded by git cl split.

R=satorux@chromium.org

Bug: 1187107
Change-Id: I6a7a39dc479265bef7c6df50b6805e61dffcceb0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2877403
Auto-Submit: David Bertoni <dbertoni@chromium.org>
Reviewed-by: Satoru Takabayashi <satorux@chromium.org>
Commit-Queue: Satoru Takabayashi <satorux@chromium.org>
Cr-Commit-Position: refs/heads/master@{#880159}
NOKEYCHECK=True
GitOrigin-RevId: c11e2c67c390b19253ae027a798bf5bd60c1f631

values_util.cc

diff --git a/values_util.cc b/values_util.cc
index 2f9f82a..6f73a84 100644
--- a/values_util.cc
+++ b/values_util.cc
@@ -270,7 +270,7 @@
       value.GetAsList(&list);
       dbus::MessageWriter array_writer(nullptr);
       writer->OpenArray("v", &array_writer);
-      for (const auto& value_in_list : *list) {
+      for (const auto& value_in_list : list->GetList()) {
         AppendValueDataAsVariant(&array_writer, value_in_list);
       }
       writer->CloseContainer(&array_writer);