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 e936f929e31cd702e530efd0845c66b074665309..513748b5ded084ea52c736cef35b9dc174032f87 100644
--- a/ash/wm/overview/window_selector_panels.cc
+++ b/ash/wm/overview/window_selector_panels.cc
@@ -199,4 +199,11 @@ void WindowSelectorPanels::SetItemBounds(aura::Window* root_window,
   }
 }
 
+void WindowSelectorPanels::ChangeItemVisibility(bool visible) {
+  for (WindowList::iterator iter = transform_windows_.begin();
+       iter != transform_windows_.end(); iter++) {
+    (*iter)->window()->layer()->SetOpacity(visible ? 1 : 0.5);

[flackr, 2014/06/26 17:33:08]

This may deserve a TODO as I think this will let you see through the individual
panels to the ones behind them which is likely to not be the desired effect.

[Nina, 2014/06/27 15:20:39]

True, I've already seen that and I don't like how it looks. Added TODO(flackr).

+  }
+}
+
 }  // namespace ash