Unable to reproduce the issue on windows 7 ans Linux Ubuntu 14.04 using chrome version 56.0.2924.28 with the below steps

1.Opened some tabs and kill the chrome 
2.start chrome with --restore-last-session
3.All tabs opened fine not observed prompt to restore last session

 ronefrati@ Please find the attached screen cast and confirm anything missed here.
Please try the issue on clean profile and update the thread if the issue still persists.

Thanks,

Deleted: 674419.mp4 2.9 MB

	674419.mp4 2.9 MB View Download

I would suggest that you open several windows each with several tabs 
This is the exact situation 

ן ,ould also suggest that you would run the  initial start chrome ( before the kill ) will also be with  --restore-last-session

The attached picture was taken while using --restore-last-session

Deleted: Capture.JPG 229 KB

	Capture.JPG 229 KB View Download

Thank you for providing more feedback. Adding requester "kavvaru@chromium.org" for another review and adding "Needs-Review" label for tracking.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

Check the bug with the following attached  file flags 
chrome://flags

Deleted: chrome___flags (1).pdf 285 KB

chrome___flags (1).pdf 285 KB Download

Google Inc.
‏Copyright 2017 Google Inc.‎. כל הזכויות שמורות.
Google Chrome	56.0.2924.28 (גירסה רשמית) beta (64 סיביות)
גרסה קודמת	5079bb60c246eb7de76df56f3335ef542f87c4c3-refs/branch-heads/2924@{#481}
מערכת הפעלה	Windows 
JavaScript	V8 5.6.326.25
Flash	24.0.0.194
User agent	Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.28 Safari/537.36
שורת פקודה 	"C:\Program Files (x86)\Google\Chrome\Application\chrome.exe" --disk-cache-dir="k:\cache" --process-per-site --flag-switches-begin --enable-browser-task-scheduler --enable-device-discovery-notifications --no-pings --disable-javascript-harmony-shipping --enable-new-bookmark-apps --enable-account-consistency --enable-apps-show-on-first-paint --enable-offer-upload-credit-cards --enable-clear-browsing-data-counters --enable-cloud-print-xps --enable-embedded-extension-options --enable-experimental-canvas-features --enable-extension-action-redesign --enable-fast-unload --enable-google-branded-context-menu --google-profile-info --enable-gpu-rasterization --enable-icon-ntp --enable-md-policy-page --enable-message-center-always-scroll-up-upon-notification-removal --new-profile-management --enable-offline-auto-reload --enable-password-generation --enable-permissions-blacklist --enable-print-preview-register-promos --enable-scroll-prediction --enable-single-click-autofill --enable-suggestions-with-substring-match --enable-tab-audio-muting --enable-use-zoom-for-dsf=true --enable-zero-copy --ignore-gpu-blacklist --enable-lcd-text --mhtml-generator-option=skip-nostore-all --nacl-debug-mask=*://*/*debug.nmf --save-page-as-mhtml --secondary-ui-md --show-autofill-type-predictions --enable-smooth-scrolling --top-chrome-md=material-hybrid --try-supported-channel-layouts --enable-features=AutomaticTabDiscarding,FramebustingNeedsSameOriginOrUserGesture,MaterialDesignHistory,MaterialDesignUserMenu,NewAudioRenderingMixingStrategy,OptimizeLoadingIPCForSmallResources,StaleWhileRevalidate2,TranslateLanguageByULP,TranslateUI2016Q2,WebAssembly,WebRTC-H264WithOpenH264FFmpeg,WebUSB,affiliation-based-matching,enable-automatic-password-saving,enable-manual-password-generation,enable-password-force-saving,password-import-export,protect-sync-credential-on-reauth --disable-features=drop-sync-credential --flag-switches-end
נתיב להפעלה	C:\Program Files (x86)\Google\Chrome\Application\chrome.exe
נתיב פרופיל	C:\Users\ronef\AppData\Local\Google\Chrome\User Data\Default
וריאציות	6a89113b-a7aa8ed
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e2b18481-5c63917a
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828a5926-8f2c913
Compiler	MSVC 2015 (PGO)

Able to reproduce the issue on windows 7 using chrome version 56.0.2924.28  
 and canary 57.0.2977.0 with the below steps

1.Launch chrome using --restore-last-session 
2.Open 2 windows with 2 tabs each
3.Kill chrome process using about:inducebrowsercrashforrealz
4.Open chrome and observe
5.Restore session popup appears and if you accept it two sessions are restored.

This is non regression issue as the issue seen from M40 builds.
Marking it as untriaged to get more inputs from dev team.

Thanks,

--restore-last-session isn't intended for general consumption. In particular it's only used (outside of tests) when chrome restarts and needs to force a restore. It's possible the case mentioned in this bug could come up during this case, but it's a very low probability. I'm closing as will not fix.

I used permanently use this command line to overcome other bug/feature which is that the restore dialog disappear after a few second and If I miss those 
second my I lose my session. 
The --restore-last-session is a very useful feature 

Do you do something to trigger the bubble closing? Or does it automatically close on you?

Automaticlly. 

I'm going to change the bubble not to close because of navigation. That work is being done under  bug 684773 . Please let me know if you still have issues after the fix lands.