[Android] Fix 'open in browser' in CCT does not work for images in Google image search
'Open in browser', 'Open in new Chrome tab' and 'Open in incognito tab'
in CCT don't work for images in Google image search. This is because
these images are both images and anchor. Their sourceUrls are data://
scheme which cannot be handled for Chrome for a View intent.
To fix the problem, since those images are also anchor and their linkUrl is
a valid url for View Intent in Chrome, thus sending linkUrl instead.
This CL also redesigns the logic for deciding the valid url of a
ContextMenuParams, that if the param is an anchor and its linkUrl is not
null, returns the linkUrl, otherwise returns the srcUrl.