Chromecast buildfix: satisfy new CreateZoomLevelDelegate API.

chromecast/browser/cast_browser_context.cc

Index: chromecast/browser/cast_browser_context.cc
diff --git a/chromecast/browser/cast_browser_context.cc b/chromecast/browser/cast_browser_context.cc
index ed19a05ef1f729cc30b8c4f239e8bb477171fbe2..e86adf2a2edc436def647c4dbe0c3b9b79b3a916 100644
--- a/chromecast/browser/cast_browser_context.cc
+++ b/chromecast/browser/cast_browser_context.cc
@@ -77,6 +77,12 @@ void CastBrowserContext::InitWhileIOAllowed() {
 #endif  // defined(OS_ANDROID)
 }
 
+scoped_ptr<content::ZoomLevelDelegate>
+CastBrowserContext::CreateZoomLevelDelegate(
+    const base::FilePath& partition_path) {
+  return nullptr;
+}
+
 base::FilePath CastBrowserContext::GetPath() const {
   return path_;
 }