Add a flag for parallel download feature in chrome://flags.

This CL adds a flag for parallel download feature.

This feature also has a finch experiment.

Doc: go/chrome-parallel-download.

Bug: 763039
Change-Id: Id6dbec1c25f430439f3967060b52c2a54f88985b
Reviewed-on: https://chromium-review.googlesource.com/656301
Commit-Queue: Xing Liu <[email protected]>
Reviewed-by: Min Qin <[email protected]>
Cr-Commit-Position: refs/heads/master@{#502389}
diff --git a/chrome/browser/about_flags.cc b/chrome/browser/about_flags.cc
index ac5ee6f..0773c2e 100644
--- a/chrome/browser/about_flags.cc
+++ b/chrome/browser/about_flags.cc
@@ -3492,6 +3492,10 @@
          ash::switches::kAshDisableTabletAutohideTitlebars)},
 #endif  // defined(OS_CHROMEOS)
 
+    {"enable-parallel-downloading", flag_descriptions::kParallelDownloadingName,
+     flag_descriptions::kParallelDownloadingDescription, kOsAll,
+     FEATURE_VALUE_TYPE(features::kParallelDownloading)},
+
     // NOTE: Adding new command-line switches requires adding corresponding
     // entries to enum "LoginCustomFlags" in histograms/enums.xml. See note in
     // enums.xml and don't forget to run AboutFlagsHistogramTest unit test.