Fix omnibox result crashes.

GetParentWidgetAndEvent can fail to find a widget; if so, don't
call through a null pointer.

BUG=883700

Change-Id: Ifa4430fe7cc7c83da9e21fa478e15b59498138ec
Reviewed-on: https://chromium-review.googlesource.com/1244019Reviewed-by: Leonard Grey <lgrey@chromium.org>
Commit-Queue: Avi Drissman <avi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#594083}

chrome/browser/ui/views/omnibox/rounded_omnibox_results_frame.cc

@@ -81,12 +81,14 @@ class TopBackgroundView : public views::View {
   // well to catch 'em all.
   void OnMouseMoved(const ui::MouseEvent& event) override {
     auto pair = GetParentWidgetAndEvent(this, &event);
-    pair.widget->OnMouseEvent(&pair.event);
+    if (pair.widget)
+      pair.widget->OnMouseEvent(&pair.event);
   }
 
   void OnMouseEvent(ui::MouseEvent* event) override {
     auto pair = GetParentWidgetAndEvent(this, event);
-    pair.widget->OnMouseEvent(&pair.event);
+    if (pair.widget)
+      pair.widget->OnMouseEvent(&pair.event);
 
     // If the original event isn't marked as "handled" then it will propagate up
     // the view hierarchy and might be double-handled. https://crbug.com/870341
@@ -95,10 +97,14 @@ class TopBackgroundView : public views::View {
 
   gfx::NativeCursor GetCursor(const ui::MouseEvent& event) override {
     auto pair = GetParentWidgetAndEvent(this, &event);
-    views::View* omnibox_view =
-        pair.widget->GetRootView()->GetEventHandlerForPoint(
-            pair.event.location());
-    return omnibox_view->GetCursor(pair.event);
+    if (pair.widget) {
+      views::View* omnibox_view =
+          pair.widget->GetRootView()->GetEventHandlerForPoint(
+              pair.event.location());
+      return omnibox_view->GetCursor(pair.event);
+    }
+
+    return nullptr;
   }
 #endif  // !USE_AURA
 };