Fix window zoom in a sane way, remove nasty casts.

content/browser/tab_contents/tab_contents.cc

Index: content/browser/tab_contents/tab_contents.cc
diff --git a/content/browser/tab_contents/tab_contents.cc b/content/browser/tab_contents/tab_contents.cc
index b2aec156db51eaf75c350ea58ce42fa3bd3067d2..8ea6a1facb30cb548397c06dbc1b69311fcef063 100644
--- a/content/browser/tab_contents/tab_contents.cc
+++ b/content/browser/tab_contents/tab_contents.cc
@@ -764,6 +764,7 @@ void TabContents::LostMouseLock() {
 }
 
 void TabContents::UpdatePreferredSize(const gfx::Size& pref_size) {
+  preferred_size_ = pref_size;
   if (delegate_)
     delegate_->UpdatePreferredSize(this, pref_size);
 }
@@ -1059,6 +1060,10 @@ int TabContents::GetMaximumZoomPercent() const {
   return maximum_zoom_percent_;
 }
 
+gfx::Size TabContents::GetPreferredSize() const {
+  return preferred_size_;
+}
+
 int TabContents::GetContentRestrictions() const {
   return content_restrictions_;
 }