Google is working on an improved UI for its PDF reader in its Chrome browser.
The current UI is rather uninformative and information-poor.
The new PDF Viewer (below) features an improved toolbar which shows Sidebar nav, PDF title, Page numbers, Zoom controls, Rotate, Fit to Page, download, and Print buttons along with additional menu at the end that shows more options when clicked., some features which can be difficult for casual users to uncover when they stumble over a PDF on the web.
The new UI is not available yet, but will initially be available under the “PDF Viewer Update” flag in Chrome://flags. Currently, the flag only shows “New PDF Viewer toolbar will appear over here”.