[Android] Add the test case about onPause and onResume.

This patch contains the test case about onPause and onResume on
embedded and shared mode.
Invoke onPause or onResume on main thread, wait for some seconds
to ensure that we get the title. Then wait for two hundred
milliseconds, get the title again. Compare the two titles.

For embedded client test:
1. install XWalkRuntimeClientEmbeddedShell.apk
2. python build/android/test_runner.py instrumentation \
--test-apk=XWalkRuntimeClientEmbeddedTest -v -f testPauseResume

For shared client test:
1. install XWalkRuntimeLib.apk
2. install XWalkRuntimeClientShell.apk
3. python build/android/test_runner.py instrumentation \
--test-apk=XWalkRuntimeClientTest -v -f testPauseResume