[Android] Enable remote debugging after rebase to M39

Adjust classes according upstream changes of DevToolsManagerDelegate
and DevToolsHttpHandlerDelegate.
Besides, hardcode webkit revision to generate remote frontend url
due to https://code.google.com/p/chromium/issues/detail?id=425912
> The fix itself doesn't work, because the frontend materials online will not change no matter how we patch our blink.
> 
> But it will fix this issue partly, by introducing a commit with "git-svn-id" in its commit log, so that when gclient sync runs with my PR in chromium-crosswalk, the WEBKIT_SVN_REVISION will get from that backported commit.

That's what I had in mind when I proposed the backport.

> I don't think it's a good approach though, it might be broken by future backport again.

True, although a bit unlikely since we can keep a close eye on what goes into blink-crosswalk and the fix will make it into the next Chromium beta. But I admit you have a point.

In any case, if we go with the hook approach we've been discussing in crosswalk-project/chromium-crosswalk#199 we could just set the revision we want in `DEPS.xwalk`, right?