Use static_cast instead of reinterpret_cast for downcasting

static_cast is better suited for downcasting since it can check that the
types are related.

/content/browser/renderer_host/render_widget_host_view_aura_browsertest.cc
This CL was uploaded by git cl split.

R=sadrul@chromium.org

Change-Id: If9ab935e6aa1dbd305c21edc4826e734c3084b42
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2435883
Auto-Submit: Kevin McNee <mcnee@chromium.org>
Reviewed-by: Sadrul Chowdhury <sadrul@chromium.org>
Commit-Queue: Sadrul Chowdhury <sadrul@chromium.org>
Cr-Commit-Position: refs/heads/master@{#811365}

content/browser/renderer_host/render_widget_host_view_aura_browsertest.cc

@@ -208,13 +208,13 @@ class RenderWidgetHostViewAuraDevtoolsBrowserTest
 
  protected:
   aura::Window* window() {
-    return reinterpret_cast<content::RenderWidgetHostViewAura*>(
+    return static_cast<content::RenderWidgetHostViewAura*>(
                shell()->web_contents()->GetRenderWidgetHostView())
         ->window();
   }
 
   bool HasChildPopup() const {
-    return reinterpret_cast<content::RenderWidgetHostViewAura*>(
+    return static_cast<content::RenderWidgetHostViewAura*>(
                shell()->web_contents()->GetRenderWidgetHostView())
         ->popup_child_host_view_;
   }