Simulate transient error and verify exponential backoff.

net/tools/testserver/testserver.py

Index: net/tools/testserver/testserver.py
diff --git a/net/tools/testserver/testserver.py b/net/tools/testserver/testserver.py
index c9444ba29d6b1fbdcd405b15da4da159b0ad72bf..c0da4ec372d5eb9920aa9e160da54d7e43b38025 100755
--- a/net/tools/testserver/testserver.py
+++ b/net/tools/testserver/testserver.py
@@ -1405,7 +1405,9 @@ class SyncPageHandler(BasePageHandler):
   def __init__(self, request, client_address, sync_http_server):
     get_handlers = [self.ChromiumSyncMigrationOpHandler,
                     self.ChromiumSyncTimeHandler,
-                    self.ChromiumSyncBirthdayErrorOpHandler]
+                    self.ChromiumSyncBirthdayErrorOpHandler,
+                    self.ChromiumSyncTransientErrorOpHandler]
+
     post_handlers = [self.ChromiumSyncCommandHandler,
                      self.ChromiumSyncTimeHandler]
     BasePageHandler.__init__(self, request, client_address,
@@ -1480,6 +1482,18 @@ class SyncPageHandler(BasePageHandler):
     self.wfile.write(raw_reply)
     return True;
 
+  def ChromiumSyncTransientErrorOpHandler(self):
+    test_name = "/chromiumsync/transienterror"
+    if not self._ShouldHandleRequest(test_name):
+      return False
+    result, raw_reply = self.server._sync_handler.HandleSetTransientError()
+    self.send_response(result)
+    self.send_header('Content-Type', 'text/html')
+    self.send_header('Content-Length', len(raw_reply))
+    self.end_headers()
+    self.wfile.write(raw_reply)
+    return True;
+
 
 def MakeDataDir():
   if options.data_dir: