aura: Fix layer type change logic.

ui/compositor/layer.cc

Index: ui/compositor/layer.cc
diff --git a/ui/compositor/layer.cc b/ui/compositor/layer.cc
index 94caf4bd2a178e5357a50a6b00c905f6f7e2ab18..b1e8f8f347c3db271576e220d723717ea6d735af 100644
--- a/ui/compositor/layer.cc
+++ b/ui/compositor/layer.cc
@@ -409,8 +409,12 @@ void Layer::SetExternalTexture(Texture* texture) {
     // Switch to a different type of layer.
 #if defined(WEBLAYER_IS_PURE_VIRTUAL)
     web_layer_->removeAllChildren();
-    content_layer_.reset();
-    solid_color_layer_.reset();
+    scoped_ptr<WebKit::WebContentLayer> old_content_layer(
+        content_layer_.release());
+    scoped_ptr<WebKit::WebSolidColorLayer> old_solid_layer(
+        solid_color_layer_.release());
+    scoped_ptr<WebKit::WebExternalTextureLayer> old_texture_layer(
+        texture_layer_.release());
     WebKit::WebLayer* new_layer = NULL;
 #else
     web_layer_.removeAllChildren();
@@ -429,8 +433,6 @@ void Layer::SetExternalTexture(Texture* texture) {
 #endif
     } else {
 #if defined(WEBLAYER_IS_PURE_VIRTUAL)
-      texture_layer_.reset();
-      solid_color_layer_.reset();
       content_layer_.reset(WebKit::WebContentLayer::create(this));
       new_layer = content_layer_->layer();
 #else