[Lookalikes] Show lookalike interstitial when site redirects to itself.

This CL is a small change that ensures lookalike sites that redirect to
themselves still see the lookalike interstitial.

Bug: 1056847
Change-Id: I52dce34ac6cb6818da638840057cf8f354c1da07
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2103072
Commit-Queue: Joe DeBlasio <jdeblasio@chromium.org>
Auto-Submit: Joe DeBlasio <jdeblasio@chromium.org>
Reviewed-by: Mustafa Emre Acer <meacer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#750298}

chrome/browser/lookalikes/lookalike_url_navigation_throttle.cc

@@ -73,7 +73,7 @@ bool IsSafeRedirect(const std::string& matching_domain,
   DCHECK_LE(first_cross_site_redirect, redirect_chain.size() - 1);
   if (first_cross_site_redirect == 0) {
     // All URLs in the redirect chain belong to the same eTLD+1.
-    return true;
+    return false;
   }
   // There is a redirect from the initial eTLD+1 to another site. In order to be
   // a safe redirect, it should be to the root of |matching_domain|. This

chrome/browser/lookalikes/lookalike_url_navigation_throttle_unittest.cc

@@ -62,6 +62,18 @@ TEST(LookalikeUrlNavigationThrottleTest, IsSafeRedirect) {
   EXPECT_FALSE(IsSafeRedirect("example.com", {GURL("http://éxample.com"),
                                               GURL("http://intermediate.com"),
                                               GURL("http://example.com")}));
+
+  // Not safe: The redirect stays unsafe from éxample.com to éxample.com.
+  EXPECT_FALSE(IsSafeRedirect(
+      "example.com", {GURL("http://éxample.com"), GURL("http://éxample.com")}));
+  // Not safe: Same, but to a path on the bad domain
+  EXPECT_FALSE(IsSafeRedirect(
+      "example.com",
+      {GURL("http://éxample.com"), GURL("http://éxample.com/path")}));
+  // Not safe: Same, but with an intermediary domain.
+  EXPECT_FALSE(IsSafeRedirect("example.com", {GURL("http://éxample.com/path"),
+                                              GURL("http://intermediate.com/p"),
+                                              GURL("http://éxample.com/dir")}));
 }
 
 }  // namespace lookalikes