Fix handling of store-write failures in Pver4

components/safe_browsing_db/v4_store_unittest.cc

 // Copyright 2016 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 "base/base64.h"
 #include "base/bind.h"
 #include "base/files/file_util.h"
 #include "base/files/scoped_temp_dir.h"
 #include "base/memory/ptr_util.h"
 #include "base/run_loop.h"
@@ skipping 807 matching lines @@
   EXPECT_EQ(69, store.file_size_);
 
   EXPECT_TRUE(another_store.VerifyChecksum());
 }
 
 TEST_F(V4StoreTest, WriteToDiskFails) {
   // Pass the directory name as file name so that when the code tries to rename
   // the temp store file to |store_path_| it fails.
   EXPECT_EQ(UNABLE_TO_RENAME_FAILURE,
             V4Store(task_runner_, temp_dir_.GetPath()).WriteToDisk(Checksum()));
+
+  // Give a location that isn't writable, even for the tmp file.
+  base::FilePath non_writable_dir =
+      temp_dir_.GetPath()
+          .Append(FILE_PATH_LITERAL("nonexistent_dir"))
+          .Append(FILE_PATH_LITERAL("some.store"));
+  EXPECT_EQ(UNEXPECTED_BYTES_WRITTEN_FAILURE,
+            V4Store(task_runner_, non_writable_dir).WriteToDisk(Checksum()));
 }
 
 TEST_F(V4StoreTest, FullUpdateFailsChecksumSynchronously) {
   V4Store store(task_runner_, store_path_);
   bool called_back = false;
   UpdatedStoreReadyCallback store_ready_callback =
       base::Bind(&V4StoreTest::UpdatedStoreReady, base::Unretained(this),
                  &called_back, false /* expect_store */);
   EXPECT_FALSE(base::PathExists(store.store_path_));
 
   // Now create a response with invalid checksum.
   std::unique_ptr<ListUpdateResponse> lur(new ListUpdateResponse);
   lur->set_response_type(ListUpdateResponse::FULL_UPDATE);
   lur->mutable_checksum()->set_sha256(std::string(crypto::kSHA256Length, 0));
   store.ApplyUpdate(std::move(lur), task_runner_, store_ready_callback);
   // The update should fail synchronously and not create a store file.
   EXPECT_FALSE(base::PathExists(store.store_path_));
 
   // Run everything on the task runner to ensure there are no pending tasks.
   task_runner_->RunPendingTasks();
   base::RunLoop().RunUntilIdle();
 
   // This ensures that the callback was called.
   EXPECT_TRUE(called_back);
   // Ensure that the file is still not created.
   EXPECT_FALSE(base::PathExists(store.store_path_));
 }
 
 }  // namespace safe_browsing