Make code path for bounds changes getting to renderer less brittle

content/browser/web_contents/web_contents_view_aura.cc

Index: content/browser/web_contents/web_contents_view_aura.cc
diff --git a/content/browser/web_contents/web_contents_view_aura.cc b/content/browser/web_contents/web_contents_view_aura.cc
index bc7ee3ada1c36fdf0dde2e5d033d022ab7f566f8..e54e082b5e19530578dba17834560846254ee7d8 100644
--- a/content/browser/web_contents/web_contents_view_aura.cc
+++ b/content/browser/web_contents/web_contents_view_aura.cc
@@ -653,7 +653,7 @@ class WebContentsViewAura::WindowObserver
  public:
   explicit WindowObserver(WebContentsViewAura* view)
       : view_(view),
-        parent_(NULL) {
+        top_level_(NULL) {
     view_->window_->AddObserver(this);
   }
 
@@ -661,20 +661,25 @@ class WebContentsViewAura::WindowObserver
     view_->window_->RemoveObserver(this);
     if (view_->window_->GetDispatcher())
       view_->window_->GetDispatcher()->RemoveRootWindowObserver(this);
-    if (parent_)
-      parent_->RemoveObserver(this);
+    if (top_level_)
+      top_level_->RemoveObserver(this);
   }
 
   // Overridden from aura::WindowObserver:
   virtual void OnWindowParentChanged(aura::Window* window,
                                      aura::Window* parent) OVERRIDE {
-    if (window == parent_)
+    if (window == top_level_)
       return;
-    if (parent_)
-      parent_->RemoveObserver(this);
-    parent_ = parent;
-    if (parent)
-      parent->AddObserver(this);
+
+    if (top_level_) {
+      top_level_->RemoveObserver(this);
+      top_level_ = NULL;
+    }
+
+    if (window && window != window->GetToplevelWindow())
+      top_level_ = window->GetToplevelWindow();
+    if (top_level_)
+      top_level_->AddObserver(this);
   }
 
   virtual void OnWindowBoundsChanged(aura::Window* window,
@@ -686,12 +691,12 @@ class WebContentsViewAura::WindowObserver
   }
 
   virtual void OnWindowAddedToRootWindow(aura::Window* window) OVERRIDE {
-    if (window != parent_)
+    if (window != top_level_)
       window->GetDispatcher()->AddRootWindowObserver(this);
   }
 
   virtual void OnWindowRemovingFromRootWindow(aura::Window* window) OVERRIDE {
-    if (window != parent_)
+    if (window != top_level_)
       window->GetDispatcher()->RemoveRootWindowObserver(this);
   }
 
@@ -710,9 +715,9 @@ class WebContentsViewAura::WindowObserver
 
   WebContentsViewAura* view_;
 
-  // We cache the old parent so that we can unregister when it's not the parent
-  // anymore.
-  aura::Window* parent_;
+  // We cache the old value so that we can unregister the observer when it
+  // changes. This also allows for filtering the events seen by the observer.
+  aura::Window* top_level_;
 
   DISALLOW_COPY_AND_ASSIGN(WindowObserver);
 };