feat: add session.downloadURL()

[miniak]

Description of Change

Add session.downloadURL() allowing to trigger downloads without a BrowserWindow

Checklist

• PR description included and stakeholders cc'd
• npm test passes
• tests are changed or added
• relevant documentation is changed or added
• PR title follows semantic commit guidelines
• PR release notes describe the change in a way relevant to app developers, and are capitalized, punctuated, and past tense.

Release Notes

Notes: Added session.downloadURL() allowing to trigger downloads without a BrowserWindow.

[deepak1556]

@miniak can you redirect the implementation of WebContents::DownloadURL to be based on this session api ?

[miniak]

@deepak1556 WebContents::DownloadURL() associates the download with the main frame of the webContents, which enforces some security checks, etc. I think the implementation has to be kept separate. Also it's not that much extra code, it's just few lines that trigger the download.

[miniak]

@deepak1556 https://cs.chromium.org/chromium/src/components/download/public/common/download_url_parameters.h?g=0&l=69-81. It should be fine for our use case, or not?

[deepak1556]

associates the download with the main frame of the webContents, which enforces some security checks, etc

Yup but those are configurable via the download parameters which could be passed into, something like

void DownloadURL(const GURL& url,
                          std::unique_ptr<download::DownloadUrlParameters> params) {}

Having these api separate sounds good too, but I would like to maintain single point of implementation that uses content api if possible , so that we don't update multiple places if chromium decides to break api signature. These are just few lines as you mentioned, so not a concern here.

[miniak]

@deepak1556 I've updated the test to use session.defaultSession instead of w.webContents.session to make it clear that the API does not need a window

[miniak]

@nornagon can you please review?

[nornagon]

Should this replace webContents.downloadURL()? i.e. should we deprecate & remove that function with this as the replacement?

[MarshallOfSound]

@nornagon See #19889 (comment)

[release-clerk]

Release Notes Persisted

Added session.downloadURL() allowing to trigger downloads without a BrowserWindow.