Update to Chromium version 70.0.3538.0 (#587811)

Known issues:
- The CefLoadCRLSetsFile function needs to be re-implemented (see issue #2497).
- Linux: GTK2 support has been removed. The cefclient sample needs to be updated
  to use GTK3 (see issue #2014).

libcef/browser/extensions/extension_host_delegate.cc

@@ -62,4 +62,16 @@ ExtensionHostQueue* CefExtensionHostDelegate::GetExtensionHostQueue() const {
   return CefExtensionsBrowserClient::Get()->GetExtensionHostQueue();
 }
 
+gfx::Size CefExtensionHostDelegate::EnterPictureInPicture(
+    content::WebContents* web_contents,
+    const viz::SurfaceId& surface_id,
+    const gfx::Size& natural_size) {
+  NOTREACHED();
+  return gfx::Size();
+}
+
+void CefExtensionHostDelegate::ExitPictureInPicture() {
+  NOTREACHED();
+}
+
 }  // namespace extensions