从顶层开始：
frameworks/base/policy/src/com/android/internal/policy/impl/PhoneWindowManager.java
函数interceptKeyBeforeQueueing
之后的流程见下图：
图中真正执行休眠唤醒的代码在
frameworks/base/services/jni/com_android_server_PowerManagerService.cpp
android_server_PowerManagerService_userActivity