chrome: Add setting for controlling the status bubble (fixes isse #3279)

This change adds `CefBrowserSettings.chrome_status_bubble` for controlling
whether the Chrome status bubble will be used.

Testable in cefclient by passing the `--hide-chrome-status-bubble`
command-line flag.

libcef/browser/chrome/browser_delegate.h

@@ -41,6 +41,12 @@ class BrowserDelegate : public content::WebContentsDelegate {
   // Add or remove ownership of the WebContents.
   virtual void SetAsDelegate(content::WebContents* web_contents,
                              bool set_delegate) = 0;
+
+  // Return true to show the status bubble. This should consistently return the
+  // same value for the lifespan of a Browser.
+  virtual bool ShowStatusBubble(bool show_by_default) {
+    return show_by_default;
+  }
 };
 
 }  // namespace cef