Fix the issue that GetFrameWindow() may change between AddObserver and RemoveObserver in KeyboardCo…

ui/keyboard/keyboard_controller.cc

Index: ui/keyboard/keyboard_controller.cc
diff --git a/ui/keyboard/keyboard_controller.cc b/ui/keyboard/keyboard_controller.cc
index ceef5941f7e424a9e912a7ad8ee0f8fe9ff73751..7abfc76d7e884407e5da67b2401e65007c9bbdb7 100644
--- a/ui/keyboard/keyboard_controller.cc
+++ b/ui/keyboard/keyboard_controller.cc
@@ -244,6 +244,10 @@ KeyboardController::~KeyboardController() {
   if (input_method_)
     input_method_->RemoveObserver(this);
   ResetWindowInsets();
+
+  for (std::set<aura::Window*>::iterator it = observed_windows_.begin();
+       it != observed_windows_.end(); ++it)
+    (*it)->RemoveObserver(window_bounds_observer_.get());
 }
 
 // static
@@ -561,6 +565,7 @@ void KeyboardController::AddBoundsChangedObserver(aura::Window* window) {
   if (target_window &&
       !target_window->HasObserver(window_bounds_observer_.get())) {
     target_window->AddObserver(window_bounds_observer_.get());
+    observed_windows_.insert(target_window);
   }
 }
 
@@ -569,6 +574,7 @@ void KeyboardController::RemoveBoundsChangedObserver(aura::Window* window) {
   if (target_window &&
       target_window->HasObserver(window_bounds_observer_.get())) {
     target_window->RemoveObserver(window_bounds_observer_.get());
+    observed_windows_.erase(target_window);
   }
 }