Check for null return from GetNativeView().

ui/keyboard/content/keyboard_ui_content.cc

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/keyboard/content/keyboard_ui_content.h"
 
 #include "base/command_line.h"
 #include "base/macros.h"
 #include "base/values.h"
 #include "content/public/browser/render_widget_host.h"
@@ skipping 220 matching lines @@
   // TODO(kevers): Add EnvObserver to properly initialize insets if a
   // window is created while the keyboard is visible.
   std::unique_ptr<content::RenderWidgetHostIterator> widgets(
       content::RenderWidgetHost::GetRenderWidgetHosts());
   while (content::RenderWidgetHost* widget = widgets->GetNextHost()) {
     content::RenderWidgetHostView* view = widget->GetView();
     // Can be NULL, e.g. if the RenderWidget is being destroyed or
     // the render process crashed.
     if (view) {
       aura::Window* window = view->GetNativeView();
+      // Added while we determine if RenderWidgetHostViewChildFrame can be
+      // changed to always return a non-null value: https://crbug.com/644726 .
+      // If we cannot guarantee a non-null value, then this may need to stay.
+      if (!window)
+        continue;
+
       if (ShouldWindowOverscroll(window)) {
         gfx::Rect window_bounds = window->GetBoundsInScreen();
         gfx::Rect intersect = gfx::IntersectRects(window_bounds,
                                                   new_bounds);
         int overlap = intersect.height();
         if (overlap > 0 && overlap < window_bounds.height())
           view->SetInsets(gfx::Insets(0, 0, overlap, 0));
         else
           view->SetInsets(gfx::Insets());
         AddBoundsChangedObserver(window);
@@ skipping 72 matching lines @@
           keyboard_controller()->keyboard_visible());
 }
 
 void KeyboardUIContent::AddBoundsChangedObserver(aura::Window* window) {
   aura::Window* target_window = window ? window->GetToplevelWindow() : nullptr;
   if (target_window)
     window_bounds_observer_->AddObservedWindow(target_window);
 }
 
 }  // namespace keyboard