Revert "Fix WebRequestProxyingURLLoaderFactory crash after redirect"

This reverts commit 066fecf.

Reason for revert: This change had some unintended effects on the interaction of WebRequest and URLLoaderThrottles.

Original change's description:
> Fix WebRequestProxyingURLLoaderFactory crash after redirect
> 
> When OnReceiveRedirect() is called, we expect to not receive any more
> events for that request until FollowRedirect() has been called and the
> request is restarted with the new URL. We were not clearing the
> bindings in this case, so the URLLoader was staying alive and calling
> OnBeforeSendHeaders() on the redirected URL. This could then result in
> OnBeforeSendHeaders() being called twice, once for the original request
> which gets redirected in //net, and once for the request in the correct
> flow when it gets restarted after FollowRedirect().
> 
> I believe this is pretty similar to the issue described in
> http://crbug.com/882661, except this one has to do with normal
> redirects instead of webRequest generated redirects.
> 
> The existing redirect tests catch this issue when using the
> 'extraHeaders' spec, so I made a version of them that runs with that
> enabled.
> 
> Bug: 918761
> Change-Id: Ifa551400e85c13ea3a297fba02a05deb5ccb1821
> Reviewed-on: https://chromium-review.googlesource.com/c/1409915
> Reviewed-by: Ken Rockot <rockot@google.com>
> Commit-Queue: Clark DuVall <cduvall@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#622685}

TBR=rockot@google.com,cduvall@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 918761
Change-Id: Ie8449c6fd6c94722ef8eb618ea1a16d429b74bbb
Reviewed-on: https://chromium-review.googlesource.com/c/1443913
Reviewed-by: Clark DuVall <cduvall@chromium.org>
Reviewed-by: John Abd-El-Malek <jam@chromium.org>
Commit-Queue: Clark DuVall <cduvall@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#627183}(cherry picked from commit 6406a9f)
Reviewed-on: https://chromium-review.googlesource.com/c/1444812
Cr-Commit-Position: refs/branch-heads/3683@{#54}
Cr-Branched-From: e510299-refs/heads/master@{#625896}

chrome/browser/extensions/api/web_request/web_request_apitest.cc

@@ -556,14 +556,6 @@ IN_PROC_BROWSER_TEST_F(ExtensionWebRequestApiTest, WebRequestRedirects) {
       << message_;
 }
 
-IN_PROC_BROWSER_TEST_F(ExtensionWebRequestApiTest,
-                       WebRequestRedirectsWithExtraHeaders) {
-  ASSERT_TRUE(StartEmbeddedTestServer());
-  ASSERT_TRUE(RunExtensionSubtestWithArg("webrequest", "test_redirects.html",
-                                         "useExtraHeaders"))
-      << message_;
-}
-
 // Tests that redirects from secure to insecure don't send the referrer header.
 IN_PROC_BROWSER_TEST_F(ExtensionWebRequestApiTest,
                        WebRequestRedirectsToInsecure) {
@@ -596,14 +588,6 @@ IN_PROC_BROWSER_TEST_F(ExtensionWebRequestApiTest,
       << message_;
 }
 
-IN_PROC_BROWSER_TEST_F(ExtensionWebRequestApiTest,
-                       WebRequestSubresourceRedirectsWithExtraHeaders) {
-  ASSERT_TRUE(StartEmbeddedTestServer());
-  ASSERT_TRUE(RunExtensionSubtestWithArg(
-      "webrequest", "test_subresource_redirects.html", "useExtraHeaders"))
-      << message_;
-}
-
 // Fails often on Windows dbg bots. http://crbug.com/177163
 #if defined(OS_WIN)
 #define MAYBE_WebRequestNewTab DISABLED_WebRequestNewTab