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

ui/views/widget/desktop_aura/desktop_window_tree_host_x11_unittest.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 <vector>
 
 #include <stddef.h>
 #include <X11/extensions/shape.h>
 #include <X11/Xlib.h>
 
@@ skipping 50 matching lines @@
     atom_cache_.reset(new ui::X11AtomCache(gfx::GetXDisplay(), kAtomsToCache));
   }
 
   ~WMStateWaiter() override {}
 
  private:
   // X11PropertyChangeWaiter:
   bool ShouldKeepOnWaiting(const ui::PlatformEvent& event) override {
     std::vector<Atom> hints;
     if (ui::GetAtomArrayProperty(xwindow(), "_NET_WM_STATE", &hints)) {
-      std::vector<Atom>::iterator it = std::find(
-          hints.begin(),
-          hints.end(),
-          atom_cache_->GetAtom(hint_));
-      bool hint_set = (it != hints.end());
+      auto it = std::find(hints.cbegin(), hints.cend(),
+                          atom_cache_->GetAtom(hint_));
+      bool hint_set = (it != hints.cend());
       return hint_set != wait_till_set_;
     }
     return true;
   }
 
   scoped_ptr<ui::X11AtomCache> atom_cache_;
 
   // The name of the hint to wait to get set or unset.
   const char* hint_;
 
@@ skipping 558 matching lines @@
   EXPECT_EQ(ui::ET_MOUSEWHEEL, second_recorder.mouse_events()[0].type());
   EXPECT_EQ(gfx::Point(-25, -25).ToString(),
             second_recorder.mouse_events()[0].location().ToString());
 
   PretendCapture(nullptr);
   first.GetNativeWindow()->RemovePreTargetHandler(&first_recorder);
   second.GetNativeWindow()->RemovePreTargetHandler(&second_recorder);
 }
 
 }  // namespace views