App launcher: Avoid a browser crash if the custom page renderer crashes.

chrome/browser/ui/app_list/app_list_view_delegate.cc

Index: chrome/browser/ui/app_list/app_list_view_delegate.cc
diff --git a/chrome/browser/ui/app_list/app_list_view_delegate.cc b/chrome/browser/ui/app_list/app_list_view_delegate.cc
index b2fae696b7ea251042dbd4f6b88fd9f270615271..b60fd13f1a3c84d2aec379bcb25671dd04b677e3 100644
--- a/chrome/browser/ui/app_list/app_list_view_delegate.cc
+++ b/chrome/browser/ui/app_list/app_list_view_delegate.cc
@@ -757,8 +757,11 @@ std::vector<views::View*> AppListViewDelegate::CreateCustomPageWebViews(
     DCHECK_EQ(profile_, web_contents->GetBrowserContext());
 
     // Make the webview transparent.
-    web_contents->GetRenderViewHost()->GetView()->SetBackgroundColor(
-        SK_ColorTRANSPARENT);
+    content::RenderWidgetHostView* render_view_host_view =
+        web_contents->GetRenderViewHost()->GetView();
+    // The RenderWidgetHostView may be null if the renderer has crashed.
+    if (render_view_host_view)
+      render_view_host_view->SetBackgroundColor(SK_ColorTRANSPARENT);
 
     views::WebView* web_view =
         new views::WebView(web_contents->GetBrowserContext());