Remove RequestTracker usage from Chrome for iOS.

RequestTracker was used for UIWebView-based Sign In.
After moving Sign In to WKWebView RequestTracker is
not needed in Chrome anymore.

Bug: 585700, 665036, 546171
Change-Id: I9c9c575ec13ebe6f4ea4d3b39a04710994cff341
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1524081
Commit-Queue: Eugene But <eugenebut@chromium.org>
Reviewed-by: Mark Cogan <marq@chromium.org>
Cr-Commit-Position: refs/heads/master@{#641227}
6 files changed