Chromium change: https://github.com/chromium/chromium/commit/902c97b0859b9a0126bc6dfd5f1b0f5e3897a031 feed modularization: move ntp.snippets to feed.sections Also: * removed the obsolete '!mHasHeader' logic in start surface. * Moved creation of section header view into FeedSurfaceCoordinator. Bug: 1254437