ash: Move VirtualKeyboardStateObserver functionality to ShellObserver

ash/common/wm_shell.cc

Index: ash/common/wm_shell.cc
diff --git a/ash/common/wm_shell.cc b/ash/common/wm_shell.cc
index 85613582b8f8acc9d42b5304f93918303b6f013a..5a29274ae240bb98f0250b40718c48cad8b8a378 100644
--- a/ash/common/wm_shell.cc
+++ b/ash/common/wm_shell.cc
@@ -46,6 +46,11 @@ void WmShell::NotifyPinnedStateChanged(WmWindow* pinned_window) {
                     OnPinnedStateChanged(pinned_window));
 }
 
+void WmShell::OnVirtualKeyboardActivated(bool activated) {
+  FOR_EACH_OBSERVER(ShellObserver, shell_observers_,
+                    OnVirtualKeyboardStateChanged(activated));
+}
+
 void WmShell::AddShellObserver(ShellObserver* observer) {
   shell_observers_.AddObserver(observer);
 }