Below are the steps to follow in chrome to set Gmail as your default email client:
1. Open Gmail in Chrome and click the Protocol Handler icon in your browser's address bar.
2. When prompted to "Allow Gmail to open all email links?", select "Use Gmail," and click "Done." Then you're done! Skip steps 3-5.
3. If you were unable to see the Protocol Handler icon overlapping-diamonds, click the Chrome menu icon chrome-menu-1 in the top right corner of your browser, and choose "Settings."
4. Click the "Show Advanced Settings" link at the bottom of the screen. Then click the "Content Settings" button under the "Privacy" header.
5. In the pop-up window, scroll down to the "Handlers" section and click the "Manage Handlers" button. Then select Gmail from the mailto dropdown, click "Done," .