Fix snapshotting on linux by creating a separate automation path for

chrome/test/webdriver/test/chromedriver_tests.py

Index: chrome/test/webdriver/test/chromedriver_tests.py
diff --git a/chrome/test/webdriver/test/chromedriver_tests.py b/chrome/test/webdriver/test/chromedriver_tests.py
index a545970959ca6ba992a3c473f597ff9863b672a4..2d23a0cfc5bbb7d1e0ca8b5d7bb46dfdf2a5a8c3 100644
--- a/chrome/test/webdriver/test/chromedriver_tests.py
+++ b/chrome/test/webdriver/test/chromedriver_tests.py
@@ -389,11 +389,6 @@ class ScreenshotTest(ChromeDriverTest):
   REDBOX = "automation_proxy_snapshot/set_size.html"
 
   def testScreenCaptureAgainstReference(self):
-    # This has regressed on linux because of tighter sandbox restrictions.
-    # See crbug.com/89777.
-    if IsLinux():
-      return
-
     # Create a red square of 2000x2000 pixels.
     url = GetFileURLForPath(os.path.join(test_paths.DataDir(),
                                          self.REDBOX))