IPC: Make ipc_perftests run on Android.

There was several minor issues:

- Base perf logging file location was off-limits on Android

- Printf needs to be flushed to be visible on Android.

- Android needs to reset the 'PipeMap' manually since we can't 'exec' after 
forking a test process. If we don't do this the Channel thinks we are in a single-
process test and tries to open an FD which was closed during forking.

- Android's base file descriptor needs to be increased to prevent stomping 
the android native logging file-descriptor with the default pipe.

- The test took too long, so the 'exponent' is reduced from 5 to 3

- We need an APK

With this patch the test runs like on other platforms, and lots of testing code is
fixed such that it works the same way on all platforms.

BUG=345471

Review URL: https://codereview.chromium.org/196343019

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@257877 0039d316-1c4b-4281-b951-d872f2087c98

• base/posix/global_descriptors.h[diff]
• base/test/multiprocess_test_android.cc[diff]
• base/test/perf_log.cc[diff]
• base/test/perf_test_suite.cc[diff]
• ipc/ipc.gyp[diff]
• ipc/ipc_channel.h[diff]
• ipc/ipc_channel_posix.cc[diff]
• ipc/ipc_multiprocess_test.cc[diff]
• ipc/ipc_perftests.cc[diff]