Use Titlebar instead of TitleBar consistently in panels code.

chrome/browser/ui/panels/panel.cc

Index: chrome/browser/ui/panels/panel.cc
diff --git a/chrome/browser/ui/panels/panel.cc b/chrome/browser/ui/panels/panel.cc
index 093441155e38948442ece0fa7b4b547849626519..1dcf1d42d70d0ec6b421740fc0faf7c5ff321802 100644
--- a/chrome/browser/ui/panels/panel.cc
+++ b/chrome/browser/ui/panels/panel.cc
@@ -57,13 +57,13 @@ void Panel::SetExpansionState(ExpansionState new_expansion_state) {
     Deactivate();
 }
 
-bool Panel::ShouldBringUpTitleBar(int mouse_x, int mouse_y) const {
+bool Panel::ShouldBringUpTitlebar(int mouse_x, int mouse_y) const {
   // Skip the expanded panel.
   if (expansion_state_ == Panel::EXPANDED)
     return false;
 
   // Let the native panel decide.
-  return native_panel_->ShouldBringUpPanelTitleBar(mouse_x, mouse_y);
+  return native_panel_->ShouldBringUpPanelTitlebar(mouse_x, mouse_y);
 }
 
 bool Panel::IsDrawingAttention() const {