Store untitled window state under load settings

This keeps untitled windows from contaminating each other by
storing to the same state path on disk but still stores state
across reloads of the windows.

Closes #599

src/app/atom.coffee

@@ -235,25 +235,40 @@ window.atom =
           sha1 = crypto.createHash('sha1').update(initialPath).digest('hex')
           filename = "editor-#{sha1}"
 
-    filename ?= 'undefined'
-    path.join(config.userStoragePath, filename)
+    if filename
+      path.join(config.userStoragePath, filename)
+    else
+      null
+
+  saveWindowState: (windowState) ->
+    windowStateJson = JSON.stringify(windowState)
+    if windowStatePath = @getWindowStatePath()
+      fsUtils.writeSync(windowStatePath, windowStateJson)
+    else
+      @getLoadSettings().windowState = windowStateJson
 
   setWindowState: (keyPath, value) ->
     windowState = @getWindowState()
     _.setValueForKeyPath(windowState, keyPath, value)
-    fsUtils.writeSync(@getWindowStatePath(), JSON.stringify(windowState))
+    @saveWindowState(windowState)
     windowState
 
   getWindowState: (keyPath) ->
-    windowStatePath = @getWindowStatePath()
-    return {} unless fsUtils.exists(windowStatePath)
+    if windowStatePath = @getWindowStatePath()
+      if fsUtils.exists(windowStatePath)
+        try
+          windowStateJson  = fsUtils.read(windowStatePath)
+        catch error
+          console.warn "Error reading window state: #{windowStatePath}", error.stack, error
+    else
+      windowStateJson = @getLoadSettings().windowState
 
     try
-      windowState = JSON.parse(fsUtils.read(windowStatePath) or '{}')
+      windowState = JSON.parse(windowStateJson or '{}')
     catch error
       console.warn "Error parsing window state: #{windowStatePath}", error.stack, error
-      windowState = {}
 
+    windowState ?= {}
     if keyPath
       _.valueForKeyPath(windowState, keyPath)
     else

src/atom-window.coffee

@@ -20,7 +20,7 @@ class AtomWindow
     try
       initialPath = path.dirname(pathToOpen) if fs.statSync(pathToOpen).isFile()
 
-    @browserWindow.loadSettings = {initialPath, bootstrapScript, resourcePath, exitWhenDone}
+    @browserWindow.loadSettings = {initialPath, bootstrapScript, resourcePath, exitWhenDone, windowState: ''}
     @browserWindow.once 'window:loaded', => @loaded = true
     @browserWindow.loadUrl "file://#{resourcePath}/static/index.html"