Use container::back() and container::pop_back() for content.

content/browser/android/content_view_core_impl.cc

 // Copyright 2012 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 "content/browser/android/content_view_core_impl.h"
 
 #include <stddef.h>
 
 #include "base/android/jni_android.h"
 #include "base/android/jni_array.h"
@@ skipping 820 matching lines @@
 }
 
 void ContentViewCoreImpl::AttachLayer(scoped_refptr<cc::Layer> layer) {
   root_layer_->InsertChild(layer, 0);
   root_layer_->SetIsDrawable(false);
 }
 
 void ContentViewCoreImpl::RemoveLayer(scoped_refptr<cc::Layer> layer) {
   layer->RemoveFromParent();
 
-  if (!root_layer_->children().size())
+  if (root_layer_->children().empty())
     root_layer_->SetIsDrawable(true);
 }
 
 void ContentViewCoreImpl::MoveRangeSelectionExtent(const gfx::PointF& extent) {
   if (!web_contents_)
     return;
 
   web_contents_->MoveRangeSelectionExtent(gfx::ToRoundedPoint(extent));
 }
 
@@ skipping 790 matching lines @@
     return ScopedJavaLocalRef<jobject>();
 
   return view->GetJavaObject();
 }
 
 bool RegisterContentViewCore(JNIEnv* env) {
   return RegisterNativesImpl(env) && JNI_DragEvent::RegisterNativesImpl(env);
 }
 
 }  // namespace content