Google is changing the way its browser handles PDF files, starting with the Chrome Canary channel. Citing security concerns, the company wants Chrome to open PDF files by default, bypassing any third-party programs such as Adobe Reader or Foxit Reader.

The modification was first noted by developer and Google open-source Chromium evangelist François Beaufort. He points to a Chromium code review that argues browsers, rather than PDF applications, should handle the opening of such documents.

Google’s argument is worth quoting in full:

PDFs in particular are safer to open in the browser. This patch changes the handling of downloads to open such files in the browser by default instead of the system handler for the file type. A “Open with system handler” menu item will be available so that users can still use the system application if needed.

The determination that a file is safer to handle in the browser is done as follows:

a) DownloadTargetDeterminer determines whether the MIME type corresponding to the target filename of the download is one which is handled by the renderer or one that is handled by a sandboxed pepper plugin. If so, then the file is considered safely handled by the browser.

b) ChromeDownloadManagerDelegate determines whether opening in the browser is preferred for the file type assuming the browser is able to handle it safely. Currently this is true for .pdf files.

Opening behavior for a download will default to opening in the browser if both results from a) and b) are true.

Google first added a PDF viewer to Chrome back in December 2010. While it can handle most PDFs and even opens them by default in some situations (such as when no PDF viewer is detected), it is very much a bare bones solution.

Most users are perfectly okay with viewing PDFs in the browser, as they only need to see a document for a short period of time and don’t want to wait for, nor need, a full-blown application. Those that work extensively with the file format, however, likely won’t be pleased with the new policy.

Google says Canary is “the most bleeding-edge official version of Chrome and somewhat of a mix between Chrome dev and the Chromium snapshot builds.” While opening PDFs by default in Canary doesn’t guarantee the change will ship in Chrome one day, Google’s lengthy explanation suggests the company has already made up its mind.

Top Image Credit: T. Al Nakib