Check RWHV for NULL before dereferencing it

Under exotic circumstances, the RenderWidgetHostView pointer returned
by host->GetView() can be NULL. Therefore, it must be tested for NULL,
before its SetBackgroundColor method is called.

Task-number: QTBUG-57826
Change-Id: Iaf3c91bdd5cb329751c29415d182bb144d01634e
(cherry picked from commit 8f9166d)
Reviewed-by: Michal Klocek <[email protected]>

Author: AlgorithMan-de

src/core/web_contents_view_qt.cpp

@@ -88,8 +88,11 @@ void WebContentsViewQt::RenderViewCreated(content::RenderViewHost* host)
 {
     // The render process is done creating the RenderView and it's ready to be routed
     // messages at this point.
-    if (m_client)
-        host->GetView()->SetBackgroundColor(toSk(m_client->backgroundColor()));
+    if (m_client && host) {
+        content::RenderWidgetHostView* rwhv = host->GetView();
+        if (rwhv)
+            rwhv->SetBackgroundColor(toSk(m_client->backgroundColor()));
+    }
 }
 
 void WebContentsViewQt::CreateView(const gfx::Size& initial_size, gfx::NativeView context)