WebView: Revise the behavior of crash handle API

To make backward compatible, kills application when render process
is killed by system.

Bug: 30824898
Test: No test, this is document revision.
Change-Id: I12862ee9ed1986ec274fe627782542e8d8414856

core/java/android/webkit/WebViewClient.java

@@ -488,7 +488,8 @@ public class WebViewClient {
      * @param view The WebView which needs to be cleaned up.
      * @param detail the reason why it exited.
      * @return true if the host application handled the situation that process has
-     *         exited, otherwise, application will crash.
+     *         exited, otherwise, application will crash if render process crashed,
+     *         or be killed if render process was killed by the system.
      */
     public boolean onRenderProcessGone(WebView view, RenderProcessGoneDetail detail) {
         return false;