The assertion error occurs if you:
1) Launch Chrome
2) Quickly move to recents

The assertion error occurs because ChromeActivity#onDeferredStartup() can be called prior to ChromeActivity#onStartWithNative()

In particular, the following occurs:
NativeInitializationController#onStart()
NativeInitializationController#onStop()
NativeInitializationController#onNativeInitializationComplete()
....
eventually
NativeInitializationController#onStart()

05-18 00:40:01.286 14375 14375 W System.err: java.lang.AssertionError
05-18 00:40:01.286 14375 14375 W System.err: 	at org.chromium.chrome.browser.metrics.UmaUtils.getForegroundStartTime(UmaUtils.java:98)
05-18 00:40:01.287 14375 14375 W System.err: 	at org.chromium.chrome.browser.ChromeActivity.postDeferredStartupIfNeeded(ChromeActivity.java:2066)
05-18 00:40:01.287 14375 14375 W System.err: 	at org.chromium.chrome.browser.ChromeActivity$6.onPageLoadFinished(ChromeActivity.java:614)
05-18 00:40:01.287 14375 14375 W System.err: 	at org.chromium.chrome.browser.tab.Tab.didFinishPageLoad(Tab.java:1523)
05-18 00:40:01.287 14375 14375 W System.err: 	at org.chromium.chrome.browser.tab.TabWebContentsObserver.didFinishLoad(TabWebContentsObserver.java:145)
05-18 00:40:01.287 14375 14375 W System.err: 	at org.chromium.content.browser.webcontents.WebContentsObserverProxy.didFinishLoad(WebContentsObserverProxy.java:169)
05-18 00:40:01.287 14375 14375 W System.err: 	at org.chromium.base.SystemMessageHandler.nativeDoRunLoopOnce(Native Method)
05-18 00:40:01.287 14375 14375 W System.err: 	at org.chromium.base.SystemMessageHandler.handleMessage(SystemMessageHandler.java:41)
05-18 00:40:01.287 14375 14375 W System.err: 	at android.os.Handler.dispatchMessage(Handler.java:102)
05-18 00:40:01.287 14375 14375 W System.err: 	at android.os.Looper.loop(Looper.java:148)
05-18 00:40:01.287 14375 14375 W System.err: 	at android.app.ActivityThread.main(ActivityThread.java:5417)
05-18 00:40:01.287 14375 14375 W System.err: 	at java.lang.reflect.Method.invoke(Native Method)
05-18 00:40:01.287 14375 14375 W System.err: 	at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
05-18 00:40:01.287 14375 14375 W System.err: 	at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)