Make Aura and compositor stacking methods more intuitive.

ui/aura/window.cc

 // Copyright (c) 2011 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 "ui/aura/window.h"
 
 #include <algorithm>
 
 #include "base/logging.h"
 #include "base/stl_util.h"
@@ skipping 178 matching lines @@
   StackChildAbove(child, children_.back());
 }
 
 void Window::StackChildAbove(Window* child, Window* other) {
   DCHECK_NE(child, other);
   DCHECK(child);
   DCHECK(other);
   DCHECK_EQ(this, child->parent());
   DCHECK_EQ(this, other->parent());
 
-  size_t child_i =
+  const size_t child_i =
       std::find(children_.begin(), children_.end(), child) - children_.begin();
-  size_t other_i =
+  const size_t other_i =
       std::find(children_.begin(), children_.end(), other) - children_.begin();
-  if (child_i > other_i)
-    return;  // Already in front of |other|.
+  if (child_i == other_i + 1)
+    return;
 
-  // Reorder children.
+  const size_t dest_i = child_i < other_i ? other_i : other_i + 1;
   children_.erase(children_.begin() + child_i);
-  children_.insert(children_.begin() + other_i, child);
+  children_.insert(children_.begin() + dest_i, child);
 
-  // Reorder the layer.
   layer()->StackAbove(child->layer(), other->layer());
 
   // Stack any transient children that share the same parent to be in front of
   // 'child'.
   Window* last_transient = child;
   for (Windows::iterator i = child->transient_children_.begin();
        i != child->transient_children_.end(); ++i) {
     Window* transient_child = *i;
     if (transient_child->parent_ == this) {
       StackChildAbove(transient_child, last_transient);
@@ skipping 312 matching lines @@
 void Window::OnStackingChanged() {
   FOR_EACH_OBSERVER(WindowObserver, observers_, OnWindowStackingChanged(this));
 }
 
 void Window::OnPaintLayer(gfx::Canvas* canvas) {
   if (delegate_)
     delegate_->OnPaint(canvas);
 }
 
 }  // namespace aura