shill: Remove trivial use of iterators

Move trivial iterations through containers from using an iterator
to using range-based for loops.  In instances where it makes sense
also use "auto" for iterators in non-trivial for loops as well.

BUG=None
TEST=Unit tests

Change-Id: I840d90fb62dc96d45f63144462b9a53b28c25ee9
Reviewed-on: https://chromium-review.googlesource.com/198051
Reviewed-by: Paul Stewart <pstew@chromium.org>
Commit-Queue: Paul Stewart <pstew@chromium.org>
Tested-by: Paul Stewart <pstew@chromium.org>
diff --git a/hook_table.cc b/hook_table.cc
index 6d23569..418ce07 100644
--- a/hook_table.cc
+++ b/hook_table.cc
@@ -74,16 +74,14 @@
   // Otherwise, if the first action completes inline, its call to
   // ActionComplete() will cause the |done| callback to be invoked before the
   // rest of the actions get started.
-  for (HookTableMap::iterator it = hook_table_.begin();
-       it != hook_table_.end(); ++it) {
-    HookAction *action = &it->second;
+  for (auto &hook_entry : hook_table_) {
+    HookAction *action = &hook_entry.second;
     action->started = true;
     action->completed = false;
   }
   // Now start the actions.
-  for (HookTableMap::iterator it = hook_table_.begin();
-       it != hook_table_.end(); ++it) {
-    it->second.start.Run();
+  for (auto &hook_entry : hook_table_) {
+    hook_entry.second.start.Run();
   }
 }