Link MediaSessionTabHelper with native MediaSession [CL is going to be split]

content/public/android/BUILD.gn

Index: content/public/android/BUILD.gn
diff --git a/content/public/android/BUILD.gn b/content/public/android/BUILD.gn
index 2633cb5e7f440207fa32c4578541aa2d0d98db45..8c61af82c3d6310916aa9da3770d18739a5eefcd 100644
--- a/content/public/android/BUILD.gn
+++ b/content/public/android/BUILD.gn
@@ -199,6 +199,7 @@ android_library("content_java") {
     "java/src/org/chromium/content_public/browser/InterfaceRegistrar.java",
     "java/src/org/chromium/content_public/browser/JavaScriptCallback.java",
     "java/src/org/chromium/content_public/browser/LoadUrlParams.java",
+    "java/src/org/chromium/content_public/browser/MediaSessionDelegate.java",
     "java/src/org/chromium/content_public/browser/MessagePort.java",
     "java/src/org/chromium/content_public/browser/MessagePortService.java",
     "java/src/org/chromium/content_public/browser/NavigationController.java",
@@ -321,6 +322,7 @@ generate_jni("content_jni_headers") {
     "java/src/org/chromium/content/browser/webcontents/WebContentsImpl.java",
     "java/src/org/chromium/content/browser/webcontents/WebContentsObserverProxy.java",
     "java/src/org/chromium/content_public/browser/LoadUrlParams.java",
+    "java/src/org/chromium/content_public/browser/MediaSessionDelegate.java",
     "java/src/org/chromium/content_public/common/MediaMetadata.java",
     "java/src/org/chromium/content_public/common/ResourceRequestBody.java",
   ]