Previously, when a cache was invalidated and every tab/iframe issued a getStyles request, we previous needlessly accessed IndexedDB for each of these requests. It happened because 1) the global cachedStyles was created only at the end of the async DB-reading, 2) and each style record is retrieved asynchronously so the single threaded JS engine interleaved all these operations. It could easily span a few seconds when many tabs are open and you have like 100 styles.
Now, in getStyles: all requests issued while cachedStyles is being populated are queued and invoked at the end.
Now, in filterStyles: all requests are cached using the request's options combined in a string as a key. It also helps on each navigation because we monitor page loading process at different stages: before, when committed, history traversal, requesting applicable styles by a content script. Icon badge update also may issue a copy of the just issued request by one of the navigation listeners.
Now, the caches are invalidated smartly: style add/update/delete/toggle only purges filtering cache, and modifies style cache in-place without re-reading the entire IndexedDB.
Now, code:false mode for manage page that only needs style meta. It reduces the transferred message size 10-100 times thus reducing the overhead caused by to internal JSON-fication in the extensions API.
Also fast&direct getStylesSafe for own pages; code cosmetics
The injection code also runs outside of onInstalled event so we check first if a content script belonging to our execution context "generation" is already injected. This can happen on browser startup: the background page is loaded in several seconds after the normal web page tabs are loaded with our content script(s) already injected. The check itself is simply a "ping" message to each tab that should return true if the content script is alive and kicking.
* hotkey to open Manage styles
* hotkey to enable/disable all styles
No default hotkeys are provided, to customize go to "Keyboard shortcuts" on the Extensions page
Push styles only to the main frame of a tab; let the content script pull styles into child frames, as before.
`chrome.tabs.sendMessage` can only broadcast to all frames in a tab until Chrome 41. The main frame always fires `onCommit` before any child frame, so only the main frame hears its own message from `onCommit`. It (and every child frame that's already fired `onCommit`) hears the `onCommit` message for every frame that follows, with the result that the main frame applies all the styles for every frame in the tab.
https://forum.userstyles.org/discussion/45062/stylish-for-chrome-1-3-0b1#Comment_95474
