media_blink_unittests: Exclude KeySystemConfigSelectorTest on Android

Bug: 608541, 840756, 842698
Change-Id: Iaaaf79dc775a6738cff55037ee9c6ff354530e19
Reviewed-on: https://chromium-review.googlesource.com/1059655Reviewed-by: Nico Weber <thakis@chromium.org>
Reviewed-by: Frank Liberato <liberato@chromium.org>
Commit-Queue: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#558755}

media/blink/BUILD.gn

@@ -168,5 +168,8 @@ test("media_blink_unittests") {
     } else {
       deps += [ "//v8:v8_external_startup_data_assets" ]
     }
+
+    # KeySystemConfigSelectorTest fails on Android (crbug.com/608541).
+    sources -= [ "key_system_config_selector_unittest.cc" ]
   }
 }