Use verbose media logging on Chromecast

On Chromecast we want media logging to be enabled on release builds by
default so that it gets recorded into device logs and sent with
feedback reports from end-users.

Review-Url: https://codereview.chromium.org/2625623002
Cr-Commit-Position: refs/heads/master@{#443150}

content/renderer/BUILD.gn

@@ -2,6 +2,7 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//build/config/chromecast_build.gni")
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//media/media_options.gni")
@@ -908,6 +909,10 @@ target(link_target_type, "renderer") {
   if (enable_ipc_fuzzer) {
     configs += [ "//tools/ipc_fuzzer:ipc_fuzzer_config" ]
   }
+
+  if (is_chromecast) {
+    defines += [ "MEDIA_EVENT_LOG_UTILITY=VLOG(1)" ]
+  }
 }
 
 # See comment at the top of //content/BUILD.gn for how this works.