media: Set MediaClientAndroid in the GPU process.

content/public/common/content_client.cc

Index: content/public/common/content_client.cc
diff --git a/content/public/common/content_client.cc b/content/public/common/content_client.cc
index 9085b752643c0a00070c8cc60220a96200a332e3..43463d548094f54c7e5cf389576ae9143e901a70 100644
--- a/content/public/common/content_client.cc
+++ b/content/public/common/content_client.cc
@@ -127,6 +127,10 @@ base::StringPiece ContentClient::GetOriginTrialPublicKey() {
 bool ContentClient::UsingSynchronousCompositing() {
   return false;
 }
+
+media::MediaClientAndroid* ContentClient::GetMediaClientAndroid() {
+  return nullptr;
+}
 #endif  // OS_ANDROID
 
 }  // namespace content