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diff --git a/chromium/docs/website/site/chromium-os/chromiumos-design-docs/text-input/syncing-input-methods/index.md b/chromium/docs/website/site/chromium-os/chromiumos-design-docs/text-input/syncing-input-methods/index.md deleted file mode 100644 index aca8b455a78..00000000000 --- a/chromium/docs/website/site/chromium-os/chromiumos-design-docs/text-input/syncing-input-methods/index.md +++ /dev/null @@ -1,102 +0,0 @@ ---- -breadcrumbs: -- - /chromium-os - - Chromium OS -- - /chromium-os/chromiumos-design-docs - - Design Documents -- - /chromium-os/chromiumos-design-docs/text-input - - Text Input -page_name: syncing-input-methods -title: Syncing Languages and Input Methods ---- - -## Background - -In M41, Chromium OS [started syncing -preferences](https://codereview.chromium.org/312023002) for languages, keyboard -layouts, and extension IMEs. Because devices may have different physical -keyboard layouts, as well as different available locales and input methods, -changes on one device should not automatically propagate to another device. -However, we still wanted to provide a convenient out-of-box experience for users -who go beyond their device's default input method when they Powerwash their -system or sign in to a new device. - -## Overview - -Instead of syncing input methods both ways, we send changes to input methods -from the device to the sync server. This lets us "remember" the most recent -settings without overwriting existing preferences on other machines. When a user -signs in to a device for the first time, we combine the input method used to -sign in with the information from the sync server, adding the user's saved input -method preferences to the local preferences without overwriting any input -methods already set up. - -For instance, a user should only have to manually add the Dvorak layout to a -device once. Then, we automatically add this layout to new devices for this -user, without affecting devices that have already been set up. If the layout -isn't available on a device, it's simply not added. In the worst case, we may -add an input method that is incompatible with the hardware keyboard, but the -user would still retain any input methods that they enabled before the first -sync. - -## Design - -### Preferences - -We kept the original unsyncable preferences, which describe the local settings: - -* **settings.language.preferred_languages:** enabled language IDs - (e.g., "en-US,fr,ko") -* **settings.language.preload_engines:** preloaded (active) component - input method IDs (e.g., "pinyin,mozc") -* **settings.language.enabled_extension_imes:** enabled extension IME - IDs - -We added three syncable preferences: - -* **settings.language.preferred_languages_syncable** -* **settings.language.preload_engines_syncable** -* **settings.language.enabled_extension_imes_syncable** - -During the first sync, the values of these preferences are merged with the local -preferences above. After that, these preferences are only used to keep track of -the user's latest settings. They never affect the settings on a device that has -already synced. In other words, they can be thought of as one-way, syncing from -the device to the sync server -- except during the first sync. - -A fourth preference was added to indicate whether the initial merging should -happen: **settings.language.merge_input_methods**. This is set to true during -OOBE. After the first sync, this is always false. This ensures that devices set -up before M41 won't have their input settings changed. - -### First Sync - -[chromeos::input_method::InputMethodSyncer](https://cs.chromium.org/chromium/src/chrome/browser/chromeos/input_method/input_method_syncer.h) -was created to handle sync logic for input methods. After the first ever sync, -MergeSyncedPrefs adds the IME settings from the syncable prefs to the local -prefs using the following algorithm for each pref: - -1. Append unique tokens from the syncable pref to the local pref. -2. Set the syncable pref equal to the merged list.\* -3. Remove tokens corresponding to values not available on this system. -4. Set the local pref equal to this validated list. - -MergeSyncedPrefs also sets merge_input_methods to false, ensuring that it won't -be called again. - -Notice that this solution doesn't assume the first sync happens right after -OOBE. For cases where users have set encryption passphrases, they could easily -add languages and input methods before enabling sync, so we support arbitrary -lists instead of single values during the merge. - -### Updates - -When a local input method pref changes, InputMethodSyncer updates the syncable -prefs to correspond to the local pref values.\* We update all three prefs at the -same time to ensure the settings are consistent -- since these will be the -values used the next time the user completes OOBE, the languages should -correspond to the input methods. - -\* For preload_engines_syncable (input method IDs), we transform the list to use -legacy component IDs so the preference can sync between Chrome OS and Chromium -OS. During first sync, we convert this back to locally valid component IDs.
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