Electron Releases

Description of Change

Fixes #52158, the recurring SIGSEGV in WebContents::DevToolsOpened() on the macOS CI shards (same bug as #29890 / #34042 / #47187).

The api::WebContents for the DevTools content::WebContents is created up front in InspectableWebContents::ShowDevTools and the handle is dropped. It's a kRemote WebContents so nothing pins it, and nothing references its wrapper again until the frontend has loaded and DevToolsOpened() stashes it in devtools_web_contents_. If a GC lands in between, the wrapper is collected but the C++ object is still findable via From() until the deferred delete runs, and FromOrCreate() hands DevToolsOpened() an empty handle.

openDevTools()                                                devtools frontend "loadCompleted"
  |                                                                          |
  ShowDevTools: FromOrCreate(devtools wc)  ->  api::WebContents #2           LoadCompleted -> DevToolsOpened
  |             (handle dropped, wrapper only weakly held)                    |  FromOrCreate(devtools wc)
  |                                                                          |
  |            GC: wrapper of #2 collected                                    |
  |            FirstWeakCallback: dead_ = true, wrapper_.Reset()              |
  |            (delete is posted, From() still finds #2)                     |
  |                  |                                                        |
  |                  +--- delete task runs before loadCompleted  ------------>|  From() finds nothing, creates #3
  |                  |                                                        |  (web-contents-created fires twice,
  |                  |                                                        |   devToolsWebContents.id != #2)
  |                  |                                                        |
  |                  +--- loadCompleted arrives before the delete  ---------->|  From() returns zombie #2
                                                                             |  GetWrapper() empty -> handle.get() == nullptr
                                                                             |  handle->owner_window() => SEGV_ACCERR
                                                                             |  (0x1e0 on main, 0x1d0 on 42-x-y = offsetof(owner_window_))

• Fix: Pin() remote api::WebContents in the constructor and Unpin() in WebContentsDestroyed(), so a remote api::WebContents lives exactly as long as its content::WebContents. Same Pinnable mechanism background pages already use, no new v8::Global.
• Regression spec forces a major GC between openDevTools() and devtools-opened and asserts exactly one DevTools api::WebContents was created and it's the one on devToolsWebContents. Fails on the pre-fix build (expected [ 2, 3 ] to deeply equal [ 3 ]), passes with the fix.
• #52166 wasn't the fix for this, it protects the inspected api::WebContents. Here that one is alive and the DevTools one is the zombie; the crash reproduced on 42-x-y with #52511 present.

Checklist

• I have built and tested this change
• I have filled out the PR description
• npm test passes (webContents module, chrome extensions, session module, webFrameMain module, BrowserWindow module devtools, MenuItems: 558 ok / 0 failing locally)
• tests are changed or added

Release Notes

Notes: Fixed a rare crash in the main process when DevTools were opened and a garbage collection ran before the DevTools frontend finished loading.