Set cleartextTrafficPermitted to true

Chrome uses MediaPlayer to handle HLS videos on Android. Starting from
Android P, the default return value for isCleartextTrafficPermitted() is
changing to false. This breaks MediaPlayer playback. We need to
explicitly set the cleartextTrafficPermitted flag, in order to maintain
the same behavior as O.

Bug: 827265
Change-Id: Id162ff32684ed0caee6e40a071892e883a44ef40
Reviewed-on: https://chromium-review.googlesource.com/988304Reviewed-by: Ted Choc <tedchoc@chromium.org>
Reviewed-by: David Benjamin <davidben@chromium.org>
Commit-Queue: Thomas Guilbert <tguilbert@chromium.org>
Cr-Commit-Position: refs/heads/master@{#547503}

chrome/android/java/res/xml/network_security_config.xml

@@ -4,7 +4,12 @@
      found in the LICENSE file. -->
 
 <network-security-config>
-    <base-config>
+    <!-- We delegate the handling of HLS videos to Android MediaPlayer. Starting
+    with Android P, the default value of isCleartextTrafficPermitted() is false.
+    This breaks our usage of MediaPlayer. We have to explicitly set
+    cleartextTrafficPermitted here to preserve functionality.
+    See https://crbug.com/827265. See also MediaPlayerRenderer. -->
+    <base-config cleartextTrafficPermitted="true">
         <trust-anchors>
             <certificates src="user"/>
             <certificates src="system"/>