Adds Window::MoveChildToFront, with surrounding changes.

ui/gfx/compositor/layer.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/gfx/compositor/layer.h"
 
 #include <algorithm>
 
 #include "base/debug/trace_event.h"
 #include "base/logging.h"
@@ skipping 97 matching lines @@
 #if defined(USE_WEBKIT_COMPOSITOR)
   child->web_layer_.removeFromParent();
 #endif
 
   RecomputeHole();
 
   child->DropTextures();
 }
 
 void Layer::MoveToFront(Layer* child) {
-  std::vector<Layer*>::iterator i =
-      std::find(children_.begin(), children_.end(), child);
-  DCHECK(i != children_.end());
-  children_.erase(i);
-  children_.push_back(child);
+  if (children_.size() <= 1 || child == children_.back())
+    return;  // Already in front.
+  MoveAbove(child, children_.back());
+}
+
+void Layer::MoveAbove(Layer* child, Layer* other) {
+  DCHECK_NE(child, other);
+  DCHECK_EQ(this, child->parent());
+  DCHECK_EQ(this, other->parent());
+  size_t child_i =
+      std::find(children_.begin(), children_.end(), child) - children_.begin();
+  size_t other_i =
+      std::find(children_.begin(), children_.end(), other) - children_.begin();
+  if (child_i > other_i)
+    return;  // Already in front of |other|.
+
+  // Reorder children.
+  children_.erase(children_.begin() + child_i);
+  children_.insert(children_.begin() + other_i, child);
+
 #if defined(USE_WEBKIT_COMPOSITOR)
   child->web_layer_.removeFromParent();
-  web_layer_.addChild(child->web_layer_);
+  web_layer_.insertChild(child->web_layer_, other_i);
 #endif
 }
 
 bool Layer::Contains(const Layer* other) const {
   for (const Layer* parent = other; parent; parent = parent->parent()) {
     if (parent == this)
       return true;
   }
   return false;
 }
@@ skipping 527 matching lines @@
 #else
     unsigned int texture_id = 0;
 #endif
     web_layer_.to<WebKit::WebExternalTextureLayer>().setTextureId(
         should_draw ? texture_id : 0);
   }
 }
 #endif
 
 }  // namespace ui