Improve panel tests by properly waiting for expected conditions.

chrome/browser/ui/panels/panel_gtk.cc

Index: chrome/browser/ui/panels/panel_gtk.cc
diff --git a/chrome/browser/ui/panels/panel_gtk.cc b/chrome/browser/ui/panels/panel_gtk.cc
index b7455e4e507799d2eb6677772cbc865f19586d6d..3f8cef192e7ba840389b9fc73b0801a76aa088ac 100644
--- a/chrome/browser/ui/panels/panel_gtk.cc
+++ b/chrome/browser/ui/panels/panel_gtk.cc
@@ -947,9 +947,12 @@ gfx::Size PanelGtk::ContentSizeFromWindowSize(
 }
 
 int PanelGtk::TitleOnlyHeight() const {
-  GtkAllocation allocation;
-  gtk_widget_get_allocation(titlebar_->widget(), &allocation);
-  return allocation.height;
+  gfx::Size& frame_size = GetFrameSize();
+  if (!frame_size.IsEmpty())
+    return frame_size.height() - kFrameBorderThickness;
+
+  NOTREACHED() << "Checking title height before window allocated";
+  return 0;
 }
 
 void PanelGtk::SetPanelAlwaysOnTop(bool on_top) {