Allow use of container cbegin() and cend() methods, plus sample uses.

ui/views/widget/desktop_aura/x11_topmost_window_finder_interactive_uitest.cc

Index: ui/views/widget/desktop_aura/x11_topmost_window_finder_interactive_uitest.cc
diff --git a/ui/views/widget/desktop_aura/x11_topmost_window_finder_interactive_uitest.cc b/ui/views/widget/desktop_aura/x11_topmost_window_finder_interactive_uitest.cc
index f5343ad5a2be6f75b4ab092604efe71f2c9ad105..46357f60f0093af2b1ee80265196eff9d348e21f 100644
--- a/ui/views/widget/desktop_aura/x11_topmost_window_finder_interactive_uitest.cc
+++ b/ui/views/widget/desktop_aura/x11_topmost_window_finder_interactive_uitest.cc
@@ -55,11 +55,9 @@ class MinimizeWaiter : public X11PropertyChangeWaiter {
   bool ShouldKeepOnWaiting(const ui::PlatformEvent& event) override {
     std::vector<Atom> wm_states;
     if (ui::GetAtomArrayProperty(xwindow(), "_NET_WM_STATE", &wm_states)) {
-      std::vector<Atom>::iterator it = std::find(
-          wm_states.begin(),
-          wm_states.end(),
-          atom_cache_->GetAtom("_NET_WM_STATE_HIDDEN"));
-      return it == wm_states.end();
+      auto it = std::find(wm_states.cbegin(), wm_states.cend(),
+                          atom_cache_->GetAtom("_NET_WM_STATE_HIDDEN"));
+      return it == wm_states.cend();
     }
     return true;
   }
@@ -97,9 +95,8 @@ class StackingClientListWaiter : public X11PropertyChangeWaiter {
     std::vector<XID> stack;
     ui::GetXWindowStack(ui::GetX11RootWindow(), &stack);
     for (size_t i = 0; i < expected_windows_.size(); ++i) {
-      std::vector<XID>::iterator it = std::find(
-          stack.begin(), stack.end(), expected_windows_[i]);
-      if (it == stack.end())
+      auto it = std::find(stack.cbegin(), stack.cend(), expected_windows_[i]);
+      if (it == stack.cend())
         return true;
     }
     return false;