I assume that it is for chrome. I have read that I can set the permissions in that file to avoid XSS errors while developing.
In linux mine are located in .config directory:
./.config/google-chrome/Default/Extensions/bjnkloegafmkhgpjglcbldhaokjpandj/1.0.0.0_0/manifest.json
./.config/google-chrome/Default/Extensions/gbammbheopgpmaagmckhpjbfgdfkpadb/1.9.1.8_0/manifest.json
./.config/google-chrome/Default/Extensions/aknpkdffaafgjchaibgeefbgmgeghloj/1.1.2.1_0/_locales/ar/messages.json
./.config/google-chrome/Default/Extensions/aknpkdffaafgjchaibgeefbgmgeghloj/1.1.2.1_0/_locales/zh-TW/messages.json
./.config/google-chrome/Default/Extensions/aknpkdffaafgjchaibgeefbgmgeghloj/1.1.2.1_0/_locales/es-419/messages.json
./.config/transmission/settings.json
./.config/transmission/stats.json