Fix windowed NPAPI plugins appearing under dialogs when DWM compositing is disabled and the tab swi…

content/browser/web_contents/web_contents_view_aura.cc

 // Copyright (c) 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/web_contents/web_contents_view_aura.h"
 
 #include "base/auto_reset.h"
 #include "base/command_line.h"
 #include "base/metrics/histogram.h"
 #include "base/strings/utf_string_conversions.h"
@@ skipping 736 matching lines @@
           view_->web_contents_->GetRenderWidgetHostView());
       if (view)
         view->UpdateConstrainedWindowRects(std::vector<gfx::Rect>());
     }
 
     // When we get parented to the root window, the code below will watch the
     // parent, aka root window. Since we already watch the root window on
     // Windows, unregister first so that the debug check doesn't fire.
     if (parent && parent == window->GetRootWindow())
       parent->RemoveObserver(this);
+
+    // We need to undo the above if we were parented to the root window and then
+    // got parented to another window. At that point, the code before the ifdef
+    // would have stopped watching the root window.
+    if (window->GetRootWindow() &&
+        parent != window->GetRootWindow() &&
+        !window->GetRootWindow()->HasObserver(this)) {
+      window->GetRootWindow()->AddObserver(this);
+    }
 #endif
 
     parent_ = parent;
     if (parent) {
       parent->AddObserver(this);
 #if defined(OS_WIN)
       if (parent != window->GetRootWindow()) {
         const aura::Window::Windows& children = parent->children();
         for (size_t i = 0; i < children.size(); ++i) {
           if (children[i] != view_->window_)
@@ skipping 15 matching lines @@
     } else {
       UpdateConstrainedWindows(NULL);
 #endif
     }
   }
 
   virtual void OnWindowAddedToRootWindow(aura::Window* window) OVERRIDE {
     if (window == view_->window_) {
       window->GetDispatcher()->AddRootWindowObserver(this);
 #if defined(OS_WIN)
-      window->GetRootWindow()->AddObserver(this);
+      if (!window->GetRootWindow()->HasObserver(this))
+        window->GetRootWindow()->AddObserver(this);
 #endif
     }
   }
 
   virtual void OnWindowRemovingFromRootWindow(aura::Window* window) OVERRIDE {
     if (window == view_->window_) {
       window->GetDispatcher()->RemoveRootWindowObserver(this);
 #if defined(OS_WIN)
       window->GetRootWindow()->RemoveObserver(this);
 
@@ skipping 902 matching lines @@
       event.location(),
       gfx::Screen::GetScreenFor(GetNativeView())->GetCursorScreenPoint(),
       ConvertAuraEventFlagsToWebInputEventModifiers(event.flags()));
   if (drag_dest_delegate_)
     drag_dest_delegate_->OnDrop();
   current_drop_data_.reset();
   return current_drag_op_;
 }
 
 }  // namespace content