Fix swiftshader include in ui/gl/BUILD.gn

BUG=None

Review URL: https://codereview.chromium.org/1640003002

Cr-Commit-Position: refs/heads/master@{#371798}

ui/gl/BUILD.gn

@@ -116,7 +116,7 @@ component("gl") {
   defines = [ "GL_IMPLEMENTATION" ]
 
   include_dirs = [
-    "//third_party/switfshader/include",
+    "//third_party/swiftshader/include",
     "//third_party/mesa/src/include",
   ]