ash: Start/stop observing KeyboardController via ShellObserver

ash/common/wm/panels/panel_layout_manager.cc

Index: ash/common/wm/panels/panel_layout_manager.cc
diff --git a/ash/common/wm/panels/panel_layout_manager.cc b/ash/common/wm/panels/panel_layout_manager.cc
index ba2b0f8ce5e4defea4963e4c99cc0d428a82bb25..4a057ea5a9e5a8658d3d41881d69a420278567b2 100644
--- a/ash/common/wm/panels/panel_layout_manager.cc
+++ b/ash/common/wm/panels/panel_layout_manager.cc
@@ -101,7 +101,7 @@ struct VisiblePanelPositionInfo {
         max_major(0),
         major_pos(0),
         major_length(0),
-        window(NULL),
+        window(nullptr),
         slide_in(false) {}
 
   int min_major;
@@ -245,9 +245,10 @@ PanelLayoutManager::PanelLayoutManager(WmWindow* panel_container)
       in_add_window_(false),
       in_layout_(false),
       show_callout_widgets_(true),
-      dragged_panel_(NULL),
+      dragged_panel_(nullptr),
       shelf_(nullptr),
-      last_active_panel_(NULL),
+      last_active_panel_(nullptr),
+      keyboard_observer_(this),
       weak_factory_(this) {
   DCHECK(panel_container);
   WmShell* shell = panel_container->GetShell();
@@ -294,7 +295,7 @@ void PanelLayoutManager::StartDragging(WmWindow* panel) {
 }
 
 void PanelLayoutManager::FinishDragging() {
-  dragged_panel_ = NULL;
+  dragged_panel_ = nullptr;
   Relayout();
 }
 
@@ -385,10 +386,10 @@ void PanelLayoutManager::OnWindowRemovedFromLayout(WmWindow* child) {
   child->GetWindowState()->RemoveObserver(this);
 
   if (dragged_panel_ == child)
-    dragged_panel_ = NULL;
+    dragged_panel_ = nullptr;
 
   if (last_active_panel_ == child)
-    last_active_panel_ = NULL;
+    last_active_panel_ = nullptr;
 
   Relayout();
 }
@@ -557,6 +558,18 @@ void PanelLayoutManager::OnShelfIconPositionsChanged() {
   Relayout();
 }
 
+void PanelLayoutManager::StartObservingKeyboard(
+    keyboard::KeyboardController* keyboard_controller) {
+  DCHECK(!keyboard_observer_.IsObservingSources());
+  keyboard_observer_.Add(keyboard_controller);
+}
+
+void PanelLayoutManager::StopObservingKeyboard(
+    keyboard::KeyboardController* keyboard_controller) {
+  if (keyboard_observer_.IsObserving(keyboard_controller))
+    keyboard_observer_.Remove(keyboard_controller);
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // PanelLayoutManager private implementation:
 
@@ -792,7 +805,7 @@ void PanelLayoutManager::UpdateStacking(WmWindow* active_panel) {
     previous_panel = it->second;
   }
 
-  previous_panel = NULL;
+  previous_panel = nullptr;
   for (std::map<int, WmWindow*>::const_reverse_iterator it =
            window_ordering.rbegin();
        it != window_ordering.rend() && it->second != active_panel; ++it) {
@@ -930,6 +943,8 @@ void PanelLayoutManager::OnKeyboardBoundsChanging(
   OnWindowResized();
 }
 
-void PanelLayoutManager::OnKeyboardClosed() {}
+void PanelLayoutManager::OnKeyboardClosed() {
+  keyboard_observer_.RemoveAll();
+}
 
 }  // namespace ash