Change to Chrome behavior for pinching to zoom in PDFs
Solution 1:
As a "workaround" to this issue, you can download BetterTouchTool and remap these gestures in Chrome:
- A "pinch in" to ⌘–
- A "pinch out" to ⌘+
That should "solve" your problem.
Solution 2:
As of September 2015, this is a bug in newer versions of Chrome that the Chrome team is aware of. [I do not know the status since then] The alternatives are to use the zoom button in the lower right, a different browser, or take the pdf out of chrome into adobe reader.