customtabs: Enable detached requests by default.

Feature has been approved to launch in M67, see
https://crbug.com/817854.

Bug: 816837
Change-Id: Ibe2699ad633b3c9ae01cbfff91293a6ab7a77859
Reviewed-on: https://chromium-review.googlesource.com/1013487Reviewed-by: Bernhard Bauer <bauerb@chromium.org>
Commit-Queue: Benoit L <lizeb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#551349}

chrome/browser/android/chrome_feature_list.cc

@@ -192,7 +192,7 @@ const base::Feature kCCTExternalLinkHandling{"CCTExternalLinkHandling",
                                              base::FEATURE_ENABLED_BY_DEFAULT};
 
 const base::Feature kCCTParallelRequest{"CCTParallelRequest",
-                                        base::FEATURE_DISABLED_BY_DEFAULT};
+                                        base::FEATURE_ENABLED_BY_DEFAULT};
 
 const base::Feature kCCTPostMessageAPI{"CCTPostMessageAPI",
                                        base::FEATURE_ENABLED_BY_DEFAULT};