Add infrastructure to run tests on android.

mojo/edk/embedder/embedder_unittest.cc

Index: mojo/edk/embedder/embedder_unittest.cc
diff --git a/mojo/edk/embedder/embedder_unittest.cc b/mojo/edk/embedder/embedder_unittest.cc
index 16a5ce2021e2f987b91414e4f7309cab9691f0e3..b138a2d67d6cf21284c88739db6463b7fd98b773 100644
--- a/mojo/edk/embedder/embedder_unittest.cc
+++ b/mojo/edk/embedder/embedder_unittest.cc
@@ -282,7 +282,13 @@ TEST_F(EmbedderTest, ChannelsHandlePassing) {
 //  10.                          (close)
 //  11.                                      (wait/cl.)
 //  12.                                                  (wait/cl.)
-TEST_F(EmbedderTest, MultiprocessChannels) {
+#if defined(OS_ANDROID)
+// Android multi-process tests are not executing the new process. This is flaky.

[viettrungluu, 2014/11/25 16:45:09]

Maybe just say "On Android we can't exec(), so we don't support multiprocess
tests."?

(Would it be flaky? Or just not work? Is what I said accurate?)

Maybe also file a bug and reference it here. (We can dream of this being
resolved someday.)

[qsr, 2014/11/25 17:17:49]

 We can exec, but with the current infrastructure for tests, there is nothing to
exec. We don't have an executable. The native code is in a .so loaded by the
java side.

+#define MAYBE_MultiprocessChannels DISABLED_MultiprocessChannels
+#else
+#define MAYBE_MultiprocessChannels MultiprocessChannels
+#endif  // defined(OS_ANDROID)
+TEST_F(EmbedderTest, MAYBE_MultiprocessChannels) {
   mojo::embedder::test::InitWithSimplePlatformSupport();
   mojo::test::MultiprocessTestHelper multiprocess_test_helper;
   multiprocess_test_helper.StartChild("MultiprocessChannelsClient");