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### Issue Details

* **Electron Version:** 10.1.6
  * <!-- (output of `node_modules/.bin/electron --version`) e.g. 4.0.3 -->
* **Operating System:** macOS Big Sur 11.0.1
  * <!-- (Platform and Version) e.g. macOS 10.13.6 / Windows 10 (1803) / Ubuntu 18.04 x64 -->
* **Last Known Working Electron version:** 10.1.5
  * <!-- (if applicable) e.g. 3.1.0 -->

### Expected Behavior
<!-- A clear and concise description of what you expected to happen. -->
`BrowserView` is not draggable.

### Actual Behavior
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`BrowserView` is draggable. 

### To Reproduce
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Your best chance of getting this bug looked at quickly is to provide an example.
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From my test, if I creates a draggable region on the left side of `BrowserWindow` (let's say with width 100px), and then add a `BrowserView` to the right side of the window, the 100px part on the right side of BrowserWindow/BrowserView will become draggable. 

You can reproduce the bugs using the following code (modified from `electron-quick-start`).
[electron-1015.zip](https://github.com/electron/electron/files/5564422/electron-1015.zip) (electron@10.1.5)
[electron-1016.zip](https://github.com/electron/electron/files/5564423/electron-1016.zip) (electron@10.1.6)

The files have identical code, except for the Electron version. It works properly in v10.1.5 but doesn't in v10.1.6

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### Screenshots
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### Additional Information
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Potentially related to https://github.com/electron/electron/pull/26145


shell/browser/api/electron_api_browser_window.cc
BaseWindow::ResetBrowserViews();
  Cleanup();
  
  weak_factory_.InvalidateWeakPtrs();
  BaseWindow::OnWindowClosed();
}
void BrowserWindow::OnWindowBlur() {
  web_contents()->StoreFocus();
  BaseWindow::OnWindowBlur();
}
void BrowserWindow::OnWindowFocus() {
  web_contents()->RestoreFocus();
#if !defined(OS_MAC)
  if (!api_web_contents_->IsDevToolsOpened())
    web_contents()->Focus();
#endif
  BaseWindow::OnWindowFocus();
}
void BrowserWindow::OnWindowIsKeyChanged(bool is_key) {