28667 Don’t use Build.VERSION_CODES.S in test (platform-android, cla: yes, waiting for tree to go green)

28694 Do not share the GrDirectContext across engine instances on Android (platform-android, cla: yes, waiting for tree to go green, needs tests)

28774 Fix Android T deprecated WindowManager INCORRECT_CONTEXT_USAGE (platform-android, cla: yes, waiting for tree to go green, needs tests)

28777 Replace jcenter() for mavenCentral() (platform-android, cla: yes, waiting for tree to go green)

28784 added unit tests for the android embedder that run on android devices (platform-android, cla: yes)

28806 Make DartExecutor.IsolateServiceIdListener public (platform-android, cla: yes, waiting for tree to go green, needs tests)