Fixed the bug when a file or files copied from Finder
Fixed the bug when a file or files copied from Finder

When a single file copied to Pasteboard, NSImage:initWithPasteboard is
not working properly. So we manually fetch the files, and init the image
with the url to that file.

BUG=553686

Steps to reproduce the problem (taken from bug report):
1. In the finder, select ONE image. Don't actually open it, just have it selected in a finder window.
2. hit cmd-c to copy
3. You can navigate to this fiddle to test: https://jsfiddle.net/syw5auys/ or set up your own paste event listener in javascript if you prefer
4. Hit cmd-v to paste

Selected file should be shown in browser.

Review URL: https://codereview.chromium.org/1445203002

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#360079}

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