Adds Cast on Android as a valid tracing configuration (chromecast_shell).

R=bulach@chromium.org
BUG=

Review URL: https://codereview.chromium.org/660683002

Cr-Commit-Position: refs/heads/master@{#299907}
diff --git a/build/android/pylib/constants.py b/build/android/pylib/constants.py
index 292ff3b..35b43422 100644
--- a/build/android/pylib/constants.py
+++ b/build/android/pylib/constants.py
@@ -67,6 +67,12 @@
         None,
         None,
         None),
+    'chromecast_shell': PackageInfo(
+        'com.google.android.apps.mediashell',
+        'com.google.android.apps.mediashell.MediaShellActivity',
+        '/data/local/tmp/castshell-command-line',
+        None,
+        None),
     'content_shell': PackageInfo(
         'org.chromium.content_shell_apk',
         'org.chromium.content_shell_apk.ContentShellActivity',