Fixed about pages cannot be synced because data is too big

[luixxiul]

Old title: About pages cannot be synced because data is too big (favicon is encoded in Base64 format) #8023 (comment)

Test plan

#8053 (comment)

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Describe the issue you encountered:

(BLESSED_EXTENSION context for cjnmeadmgmiihncdidmfiabhenbggfjm) chrome-extension://cjnmeadmgmiihncdidmfiabhenbggfjm/content/scripts/sync.js:3: Uncaught Error: Data is too big; part limit is 64.{Error: Data is too big; part limit is 64.
    at Object.module.exports.encodeDataToS3KeyArray (chrome-extension://cjnmeadmgmiihncdidmfiabhenbggfjm/content/scripts/sync.js:3:28981)
    at RequestUtil.put (chrome-extension://cjnmeadmgmiihncdidmfiabhenbggfjm/content/scripts/sync.js:1:13433)
    at records.forEach.record (chrome-extension://cjnmeadmgmiihncdidmfiabhenbggfjm/content/scripts/sync.js:2:2197)
    at Array.forEach (native)
    at EventEmitter2.ipc.on (chrome-extension://cjnmeadmgmiihncdidmfiabhenbggfjm/content/scripts/sync.js:2:1873)
    at EventEmitter2.emit (extensions::event_emitter:43:17)
    at EventEmitter2.ipcRenderer.emit (extensions::ipc_utils:31:22)}

• Platform (Win7, 8, 10? macOS? Linux distro?): Windows 10 32 bit

• Brave Version (revision SHA): 0.14.1 RC1

• Steps to reproduce:

  1. Set up sync
  2. Open about:about and bookmark it
  3. Open chrome-extension://cjnmeadmgmiihncdidmfiabhenbggfjm/_generated_background_page.html and wait

• Actual result: the error above is returned

• Expected result: either favicon is replaced with a link or data limit is increased to sync the about pages

• Extra QA steps:
  1.
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• Screenshot if needed:
  

• Any related issues:

[diracdeltas]

I think we shouldn't sync data: favicons. Maybe just strip out the favicon for now if it is a data: url.

[ayumi]

the max record size should be ~50 KiB.
however i agree we don't need to sync data URIs.