[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, sleep two seconds to
wait for the action is finished, get the title. Then sleep two
hundred milliseconds, get the title. 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