Added text filtering to Overview Mode

ash/wm/overview/window_selector_panels.cc

Index: ash/wm/overview/window_selector_panels.cc
diff --git a/ash/wm/overview/window_selector_panels.cc b/ash/wm/overview/window_selector_panels.cc
index e4ab9bea2bfce8e89bb1a67c482cfc65eaa69671..d3c69201e47fc90776b0449da8a28f6c93591a7c 100644
--- a/ash/wm/overview/window_selector_panels.cc
+++ b/ash/wm/overview/window_selector_panels.cc
@@ -205,4 +205,14 @@ void WindowSelectorPanels::SetItemBounds(aura::Window* root_window,
   }
 }
 
+void WindowSelectorPanels::SetOpacity(float opacity) {
+  // TODO(flackr): find a way to make panels that are hidden behind other panels
+  // look nice.
+  for (WindowList::iterator iter = transform_windows_.begin();
+       iter != transform_windows_.end(); iter++) {
+    (*iter)->window()->layer()->SetOpacity(opacity);
+  }
+  WindowSelectorItem::SetOpacity(opacity);
+}
+
 }  // namespace ash