content_shell: Move BrowserTestSystemMessageHandler and use it in layout tests for Android

content/public/test/browser_test_message_pump_android.cc

Index: content/public/test/browser_test_message_pump_android.cc
diff --git a/content/test/browser_test_message_pump_android.cc b/content/public/test/browser_test_message_pump_android.cc
similarity index 98%
rename from content/test/browser_test_message_pump_android.cc
rename to content/public/test/browser_test_message_pump_android.cc
index f992110e234b1ddb8a58595b95d39d725ae66e58..a6b908a2c4829e5a8b4c00b66f72db1939fcccbc 100644
--- a/content/test/browser_test_message_pump_android.cc
+++ b/content/public/test/browser_test_message_pump_android.cc
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "content/test/browser_test_message_pump_android.h"
+#include "content/public/test/browser_test_message_pump_android.h"
 
 #include "base/android/jni_android.h"
 #include "base/android/scoped_java_ref.h"