Activity的onContentChange,onAttac

1.onContentChange:在onCreate中调用setContentView()方法时回调。

Activity.onCreate>Activity.setContentView>getWindow().setContenView
>PhoneWindow.setContentView()>Activity.onContentChanged

2.onAttachedToWindow:在view渲染之前回调，具体的是指ViewRootImpl. performTraversals()方法中调用。

Activity.onCreate->Activity.onStart->Activity.onResume->WindowManager.addView(DecorView,l)->WindowMangerImpl.addView
>WindowMangerGlobal.addView->ViewRootImpl.setView
>ViewRootImpl.requestLayout->ViewRootImpl.performTraversals->DecorView.onAttachedToWindow(依次调用DecorView.onAttachedToWindow,所有子View的onAttachedToWindow，最后调用Activity.onAttachedToWindow，然后开始View树渲染流程的调用)->performMeasure->performLayout->performDraw

3.onWindowFocuseChanged(hasFocus: Boolean)：Activity第一帧渲染完成后开始回调，该方法会调用多次，比如在Activity上面显示Dialog,pop等对应着hasFocus值的改变。

DecorView.onMeasure>DecorView.onLayout>DecorView.onDraw>View.onFocuseChanged->ViewGroup.onFocusChanged->Activity.onFocuseChanged