4e6b7d2ee9
Change-Id: I719d6545f0ed2fc9bae19fa36cf99c1dd4308562 Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2429932 Commit-Queue: David Bienvenu <davidbienvenu@chromium.org> Reviewed-by: Jesse McKenna <jessemckenna@google.com> Cr-Commit-Position: refs/heads/master@{#810414}
79 lines
4.7 KiB
Markdown
79 lines
4.7 KiB
Markdown
# Windows Progressive Web App integration
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## Desktop Shortcuts
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When a Progressive Web App (PWA) is installed on Windows, Chrome creates a
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desktop shortcut to the PWA, with the PWA icon. The shortcut launches a small
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Chrome binary chrome_proxy.exe with the app id of the PWA, and the Chrome
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profile the PWA is installed in. When chrome_proxy.exe runs, it launches Chrome
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with the same command line options. The shortcut links to chrome_proxy.exe
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instead of chrome.exe because of
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[a bug in Windows 10 start menu pinning](https://source.chromium.org/chromium/chromium/src/+/master:chrome/chrome_proxy/chrome_proxy_main_win.cc;l=23).
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## File handling support
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In order to make Progressive Web Apps (PWA's) more like traditional apps, PWA's
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support opening files on the user's desktop. On Windows, when a PWA is
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installed, if the PWA's manifest lists one or more file extension types that it
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supports opening, Chrome registers the PWA as a handler for the file
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extension(s), in the Windows registry. When the user right clicks on a file with
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a registered extension, the PWA name and custom icon appears in the list of
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applications that can open the file. The user can also set the PWA as the
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default handler for the file extension.
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Because of a limitation of the Windows shell, Chrome registers a per-PWA install
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[launcher app](https://source.chromium.org/chromium/chromium/src/+/master:chrome/browser/web_applications/chrome_pwa_launcher/README.md;l=1)
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as a handler for the file extension. Chrome ships with a canonical launcher app
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called chrome_pwa_launcher.exe, which lives in the version sub-directory of the
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Chrome install dir. When a PWA is installed, we create a hard link from the
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PWA install dir `<profile_dir>/Web Applications/<app_id>` to the canonical launcher
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app. If the hard link fails (e.g., Chrome install dir is on a different drive
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than the profile dir), we copy the launcher app to the PWA install dir. In either
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case, the name of the launcher app in the PWA install dir is a sanitized version
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of the PWA name.
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Registration starts in [web_app::RegisterFileHandlersWithOS](https://source.chromium.org/search?q=RegisterFileHandlersWithOS%20file:_win.cc&sq=),
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and works as follows: we create a unique
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[ProgID](https://docs.microsoft.com/en-us/windows/win32/com/-progid--key)
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for the PWA installation with the following format:
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`<BaseAppId>.<hash(Profile + AppID)>`
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We use the hash due to 32-character limit for ProgID's. The registry work is
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done in
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[ShellUtil::AddFileAssociations](https://source.chromium.org/chromium/chromium/src/+/master:chrome/installer/util/shell_util.cc?q=%20ShellUtil::AddFileAssociations):
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* Register the ProgID by adding `key HKCU\Software\Classes\<progID>` to the registry.
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* Set the application name and icon for the PWA with these two keys:
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* `HKCU\Software\Classes\<progID>\Application::ApplicationIcon = <path to icon in PWA install dir>,0`
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* `HKCU\Software\Classes\<progID>\Application::ApplicationName = <PWA name>`
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* Hook up the command to launch the launcher app
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* `HKCU\Software\Classes\<progID>\shell\open\command = <launcher_app_path_in_profile> --app-id=<app_id> --profile-directory=<profile_dir>`
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* Add a key to keep track of the file extensions registered for a progId,
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for ease of uninstallation:
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* `HKCU\Software\Classes\<progId>\File Extensions = <semicolon delimited list of extensions>`
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When Chrome is launched, it writes its path into the "Last Browser" file in
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the User Data dir.
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When the launcher app is run, it launches Chrome using the path written into the
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"Last Browser" file. Because the launcher app is in a sub-directory of the profile
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directory, the "Last Browser" file is in its great grandparent directory.
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When a new version of Chrome is installed, we need to update the hard links
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to and copies of the installed launcher apps to use the newly installed canonical
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launcher app. This is done by having the launcher app pass its version to Chrome, when
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launching Chrome. If the launcher app is out of date, Chrome updates all the
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launcher apps in the current user data dir.
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When a PWA is uninstalled, we unregister the PWA as a handler for the file
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extensions it was registered for. When a PWA changes the file extensions it can
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handle, we update the registry.
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## Miscellaneous
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* If the same PWA is registered in multiple profiles, we distinguish them by
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adding the profile name in parentheses to the PWA name, e.g,
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"Example PWA (profile1)". If a PWA is uninstalled from a profile, and there is
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one remaining install in another profile, we remove the profile name from the
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application name.
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* Windows 7 does not support some of the registry entries needed to set the
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name and icon for a PWA. So, the file open context menu item for a PWA on
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Windows 7 gets its name from the launcher app created for the PWA, and uses a
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generic PWA icon.
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