Add sourcePath parameter to StyleManager::addStyleSheet

src/style-manager.coffee

@@ -5,6 +5,7 @@ class StyleManager
   constructor: ->
     @emitter = new Emitter
     @styleElements = []
+    @styleElementsBySourcePath = {}
 
   onDidAddStyleSheet: (callback) ->
     @emitter.on 'did-add-style-sheet', callback
@@ -12,19 +13,35 @@ class StyleManager
   onDidRemoveStyleSheet: (callback) ->
     @emitter.on 'did-remove-style-sheet', callback
 
+  onDidUpdateStyleSheet: (callback) ->
+    @emitter.on 'did-update-style-sheet', callback
+
   getStyleElements: ->
     @styleElements.slice()
 
-  addStyleSheet: (source) ->
-    styleElement = document.createElement('style')
+  addStyleSheet: (source, params) ->
+    sourcePath = params?.sourcePath
+    if sourcePath? and styleElement = @styleElementsBySourcePath[sourcePath]
+      updated = true
+    else
+      styleElement = document.createElement('style')
+
     styleElement.textContent = source
+
     @styleElements.push(styleElement)
-    @emitter.emit 'did-add-style-sheet', {styleElement}
+    @styleElementsBySourcePath[sourcePath] ?= styleElement if sourcePath?
 
-    new Disposable => @removeStyleElement(styleElement)
+    if updated
+      @emitter.emit 'did-update-style-sheet', {styleElement, sourcePath}
+    else
+      @emitter.emit 'did-add-style-sheet', {styleElement, sourcePath}
 
-  removeStyleElement: (styleElement) ->
+    new Disposable => @removeStyleElement(styleElement, params)
+
+  removeStyleElement: (styleElement, params) ->
     index = @styleElements.indexOf(styleElement)
     unless index is -1
       @styleElements.splice(index, 1)
+      sourcePath = params?.sourcePath
+      delete @styleElementsBySourcePath[sourcePath] if sourcePath?
       @emitter.emit 'did-remove-style-sheet', {styleElement}