Update Chromium

Pull in the last of the changes of the Chrome 55 backports.

Change-Id: I9f6bf3996045355b60841788d27c9379925a79a4
Reviewed-by: Alexandru Croitor <[email protected]>

Author: Allan Sandfeld Jensen

dist/changes-5.6.3

@@ -34,7 +34,7 @@ information about a particular change.
       CVE-2016-5187, CVE-2016-5188, CVE-2016-5192, CVE-2016-5198.
       CVE-2016-5205, CVE-2016-5207, CVE-2016-5208, CVE-2016-5214,
       CVE-2016-5215, CVE-2016-5221, CVE-2016-5222, CVE-2016-5224,
-      CVE-2016-5225, CVE-2016-9650, CVE-2016-9652
+      CVE-2016-5225, CVE-2016-9650, CVE-2016-9651, CVE-2016-9652
    * Added support for macOS 10.12 Sierra.
    * Backported various crash and assertion fixes.