Patch by Thatcher Ulrich <tulrich@google.com>.

Implement "iframe shim" behavior for windowed plugins.

In FF and IE on windows, iframes are implemented as native HWNDs.  
This has the side effect that iframes display on top of windowed 
plugins. This side effect has long been known as a workaround for
allowing HTML elements to appear above plugin content.

BUG=1788

Review URL: http://codereview.chromium.org/7032

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@3137 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 73 insertions, 0 deletions

diff --git a/webkit/glue/stacking_order_iterator.h b/webkit/glue/stacking_order_iterator.h
new file mode 100755
index 0000000..20dea41
--- /dev/null
+++ b/webkit/glue/stacking_order_iterator.h
@@ -0,0 +1,73 @@
+// Copyright (c) 2006-2008 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.
+
+// Provides some utilities for iterating over a RenderObject graph in
+// stacking order.
+
+#ifndef WEBKIT_GLUE_STACKING_ORDER_ITERATOR_H__
+#define WEBKIT_GLUE_STACKING_ORDER_ITERATOR_H__
+
+#include <vector>
+
+namespace WebCore {
+class RenderLayer;
+class RenderObject;
+}
+
+// Iterates over a subtree of RenderLayers in stacking order, back to
+// front.  Modifying the RenderObject graph invalidates this iterator.
+//
+// TODO(tulrich): this could go in webkit.
+// TODO(tulrich): needs unittests.
+class RenderLayerIterator {
+ public:
+  RenderLayerIterator();
+
+  // Sets the RenderLayer subtree to iterate over.
+  void Reset(WebCore::RenderLayer* rl);
+
+  // Returns the next RenderLayer in stacking order, back to front.
+  WebCore::RenderLayer* Next();
+ private:
+  class Context {
+   public:
+    Context(WebCore::RenderLayer* layer);
+
+    bool HasMoreNeg();
+    Context NextNeg();
+    bool HasSelf();
+    WebCore::RenderLayer* NextSelf();
+    bool HasMoreOverflow();
+    Context NextOverflow();
+    bool HasMorePos();
+    Context NextPos();
+
+   private:
+    WebCore::RenderLayer* layer_;
+    size_t next_neg_;
+    size_t next_self_;
+    size_t next_overflow_;
+    size_t next_pos_;
+  };
+
+  std::vector<Context> context_stack_;
+};
+
+// Iterates over a subtree of RenderObjects below a given RenderLayer.
+//
+// TODO(tulrich): this could go in webkit.
+// TODO(tulrich): needs unittests.
+class StackingOrderIterator {
+ public:
+  StackingOrderIterator();
+  void Reset(WebCore::RenderLayer* rl);
+  WebCore::RenderObject* Next();
+
+ private:
+  RenderLayerIterator layer_iterator_;
+  WebCore::RenderObject* current_object_;
+  WebCore::RenderObject* current_layer_root_;
+};
+
+#endif  // WEBKIT_GLUE_STACKING_ORDER_ITERATOR_H__