Add infrastructure to run tests on android.

mojo/edk/system/core_unittest.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "mojo/edk/system/core.h"
 
 #include <stdint.h>
 
 #include <limits>
 
@@ skipping 874 matching lines @@
   EXPECT_EQ(0u, hss.satisfied_signals);
   EXPECT_EQ(MOJO_HANDLE_SIGNAL_READABLE, hss.satisfiable_signals);
   hss = kFullMojoHandleSignalsState;
   EXPECT_EQ(
       MOJO_RESULT_DEADLINE_EXCEEDED,
       core()->Wait(ch, MOJO_HANDLE_SIGNAL_READABLE, 0, MakeUserPointer(&hss)));
   EXPECT_EQ(0u, hss.satisfied_signals);
   EXPECT_EQ(MOJO_HANDLE_SIGNAL_READABLE, hss.satisfiable_signals);
 
   // Write.
-  char elements[2] = {'A', 'B'};
+  signed char elements[2] = {'A', 'B'};
   uint32_t num_bytes = 2u;
   EXPECT_EQ(MOJO_RESULT_OK,
             core()->WriteData(ph, UserPointer<const void>(elements),
                               MakeUserPointer(&num_bytes),
                               MOJO_WRITE_DATA_FLAG_NONE));
   EXPECT_EQ(2u, num_bytes);
 
   // Consumer should now be readable.
   hss = kEmptyMojoHandleSignalsState;
   EXPECT_EQ(MOJO_RESULT_OK, core()->Wait(ch, MOJO_HANDLE_SIGNAL_READABLE, 0,
@@ skipping 368 matching lines @@
   EXPECT_EQ(MOJO_RESULT_OK, core()->Close(h_passing[1]));
   EXPECT_EQ(MOJO_RESULT_OK, core()->Close(ph));
   EXPECT_EQ(MOJO_RESULT_OK, core()->Close(ch));
 }
 
 // TODO(vtl): Test |DuplicateBufferHandle()| and |MapBuffer()|.
 
 }  // namespace
 }  // namespace system
 }  // namespace mojo