Fix tests when run against ChromiumEnv

There are a couple differences between ChromiumEnv and
PosixEnv/WindowsEnv which cause test failures that are fixed (or at
least patched over) in this change:

* NewSequentialFile() and NewRandomAccessFile() return Status::IOError
  rather than Status::NotFound when a file is not found, due to
  https://crbug.com/760362. This means a few tests need to expect a
  different error result.
* GetChildren() never returns the '.' or '..' entries.
* As allowed by the documentation for Env::Schedule(), ChromiumEnv may
  execute functions on multiple threads and guarantees no sequencing.
  EnvTest.RunMany assumed that functions ran in order. The test has been
  updated.

db/db_test.cc

@@ -1722,8 +1722,13 @@ TEST_F(DBTest, DestroyEmptyDir) {
   ASSERT_TRUE(env.FileExists(dbname));
   std::vector<std::string> children;
   ASSERT_LEVELDB_OK(env.GetChildren(dbname, &children));
+#if defined(LEVELDB_PLATFORM_CHROMIUM)
+  // Chromium's file system abstraction always filters out '.' and '..'.
+  ASSERT_EQ(0, children.size());
+#else
   // The stock Env's do not filter out '.' and '..' special files.
   ASSERT_EQ(2, children.size());
+#endif  // defined(LEVELDB_PLATFORM_CHROMIUM)
   ASSERT_LEVELDB_OK(DestroyDB(dbname, opts));
   ASSERT_TRUE(!env.FileExists(dbname));
 

db/recovery_test.cc

@@ -328,7 +328,12 @@ TEST_F(RecoveryTest, ManifestMissing) {
   RemoveManifestFile();
 
   Status status = OpenWithStatus();
+#if defined(LEVELDB_PLATFORM_CHROMIUM)
+  // TODO(crbug.com/760362): See comment in MakeIOError() from env_chromium.cc.
+  ASSERT_TRUE(status.IsIOError());
+#else
   ASSERT_TRUE(status.IsCorruption());
+#endif  // defined(LEVELDB_PLATFORM_CHROMIUM)
 }
 
 }  // namespace leveldb

util/env_test.cc

@@ -96,40 +96,45 @@ TEST_F(EnvTest, RunMany) {
   struct RunState {
     port::Mutex mu;
     port::CondVar cvar{&mu};
-    int last_id = 0;
+    int run_count = 0;
   };
 
   struct Callback {
-    RunState* state_;  // Pointer to shared state.
-    const int id_;  // Order# for the execution of this callback.
+    RunState* const state_;  // Pointer to shared state.
+    bool run = false;
 
-    Callback(RunState* s, int id) : state_(s), id_(id) {}
+    Callback(RunState* s) : state_(s) {}
 
     static void Run(void* arg) {
       Callback* callback = reinterpret_cast<Callback*>(arg);
       RunState* state = callback->state_;
 
       MutexLock l(&state->mu);
-      ASSERT_EQ(state->last_id, callback->id_ - 1);
-      state->last_id = callback->id_;
+      state->run_count++;
+      callback->run = true;
       state->cvar.Signal();
     }
   };
 
   RunState state;
-  Callback callback1(&state, 1);
-  Callback callback2(&state, 2);
-  Callback callback3(&state, 3);
-  Callback callback4(&state, 4);
+  Callback callback1(&state);
+  Callback callback2(&state);
+  Callback callback3(&state);
+  Callback callback4(&state);
   env_->Schedule(&Callback::Run, &callback1);
   env_->Schedule(&Callback::Run, &callback2);
   env_->Schedule(&Callback::Run, &callback3);
   env_->Schedule(&Callback::Run, &callback4);
 
   MutexLock l(&state.mu);
-  while (state.last_id != 4) {
+  while (state.run_count != 4) {
     state.cvar.Wait();
   }
+
+  ASSERT_TRUE(callback1.run);
+  ASSERT_TRUE(callback2.run);
+  ASSERT_TRUE(callback3.run);
+  ASSERT_TRUE(callback4.run);
 }
 
 struct State {
@@ -175,11 +180,21 @@ TEST_F(EnvTest, TestOpenNonExistentFile) {
   RandomAccessFile* random_access_file;
   Status status =
       env_->NewRandomAccessFile(non_existent_file, &random_access_file);
+#if defined(LEVELDB_PLATFORM_CHROMIUM)
+  // TODO(crbug.com/760362): See comment in MakeIOError() from env_chromium.cc.
+  ASSERT_TRUE(status.IsIOError());
+#else
   ASSERT_TRUE(status.IsNotFound());
+#endif  // defined(LEVELDB_PLATFORM_CHROMIUM)
 
   SequentialFile* sequential_file;
   status = env_->NewSequentialFile(non_existent_file, &sequential_file);
+#if defined(LEVELDB_PLATFORM_CHROMIUM)
+  // TODO(crbug.com/760362): See comment in MakeIOError() from env_chromium.cc.
+  ASSERT_TRUE(status.IsIOError());
+#else
   ASSERT_TRUE(status.IsNotFound());
+#endif  // defined(LEVELDB_PLATFORM_CHROMIUM)
 }
 
 TEST_F(EnvTest, ReopenWritableFile) {