Fix a queue for FSP API.

chrome/browser/chromeos/file_system_provider/queue_unittest.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/chromeos/file_system_provider/queue.h"
 
 #include <vector>
 
 #include "base/files/file.h"
 #include "base/run_loop.h"
@@ skipping 95 matching lines @@
   queue.Remove(second_token);
   base::RunLoop().RunUntilIdle();
   EXPECT_EQ(1, first_counter);
   EXPECT_EQ(0, first_abort_counter);
   EXPECT_EQ(1, second_counter);
   EXPECT_EQ(1, second_abort_counter);
   EXPECT_EQ(1, third_counter);
   EXPECT_EQ(0, third_abort_counter);
 }
 
+TEST_F(FileSystemProviderQueueTest, Enqueue_WhilePreviousNotRemoved) {
+  Queue queue(1);
+  const size_t first_token = queue.NewToken();
+  int first_counter = 0;
+  int first_abort_counter = 0;
+  queue.Enqueue(first_token,
+                base::Bind(&OnRun, &first_counter, &first_abort_counter));
+
+  base::RunLoop().RunUntilIdle();
+  queue.Complete(first_token);
+
+  // Enqueuing a new task must not start it, once the queue is filled with a
+  // completed task.
+  const size_t second_token = queue.NewToken();
+  int second_counter = 0;
+  int second_abort_counter = 0;
+  queue.Enqueue(second_token,
+                base::Bind(&OnRun, &second_counter, &second_abort_counter));
+
+  base::RunLoop().RunUntilIdle();
+  EXPECT_EQ(0, second_counter);
+  EXPECT_EQ(0, second_abort_counter);
+}
+
 TEST_F(FileSystemProviderQueueTest, Enqueue_MultipleAtOnce) {
   Queue queue(2);
   const size_t first_token = queue.NewToken();
   int first_counter = 0;
   int first_abort_counter = 0;
   queue.Enqueue(first_token,
                 base::Bind(&OnRun, &first_counter, &first_abort_counter));
 
   const size_t second_token = queue.NewToken();
   int second_counter = 0;
@@ skipping 223 matching lines @@
 
   base::RunLoop().RunUntilIdle();
   EXPECT_EQ(1, first_counter);
   EXPECT_EQ(1, first_abort_counter);
   EXPECT_EQ(0, second_counter);
   EXPECT_EQ(0, second_abort_counter);
 }
 
 }  // namespace file_system_provider
 }  // namespace chromeos