Enable Assistant MediaSession Integration.

CQ_INCLUDE_TRYBOTS=luci.chrome.try:linux-chromeos-chrome

Bug: b:129715312
Test: Manual
Change-Id: Ie7d9eab6c7e9d7191ffc1260b5bcc4c73b11b6c5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1553664Reviewed-by: Xiaohui Chen <xiaohuic@chromium.org>
Commit-Queue: Li Lin <llin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#649787}

chromeos/services/assistant/public/features.cc

@@ -63,8 +63,7 @@ const base::Feature kScreenContextQuery{"ChromeOSAssistantScreenContextQuery",
                                         base::FEATURE_DISABLED_BY_DEFAULT};
 
 const base::Feature kEnableMediaSessionIntegration{
-    "AssistantEnableMediaSessionIntegration",
-    base::FEATURE_DISABLED_BY_DEFAULT};
+    "AssistantEnableMediaSessionIntegration", base::FEATURE_ENABLED_BY_DEFAULT};
 
 bool IsAppSupportEnabled() {
   return base::FeatureList::IsEnabled(