Enable parallel download for QUIC and HTTP2 by default

The finch experiment already launches.
Default the flag values to enabled.

BUG=971366

Change-Id: I8ab291b6c020e521094c3cc12e76e6a5d9918f7d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2096794Reviewed-by: Xing Liu <xingliu@chromium.org>
Commit-Queue: Min Qin <qinmin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#752509}

components/download/public/common/download_features.cc

@@ -53,10 +53,10 @@ const base::Feature kUseParallelRequestsForUnknwonRangeSupport{
     base::FEATURE_ENABLED_BY_DEFAULT};
 
 const base::Feature kUseParallelRequestsForHTTP2{
-    "UseParallelRequestsForHTTP2", base::FEATURE_DISABLED_BY_DEFAULT};
+    "UseParallelRequestsForHTTP2", base::FEATURE_ENABLED_BY_DEFAULT};
 
 const base::Feature kUseParallelRequestsForQUIC{
-    "UseParallelRequestsForQUIC", base::FEATURE_DISABLED_BY_DEFAULT};
+    "UseParallelRequestsForQUIC", base::FEATURE_ENABLED_BY_DEFAULT};
 
 const base::Feature kDeleteExpiredDownloads{"DeleteExpiredDownloads",
                                             base::FEATURE_ENABLED_BY_DEFAULT};