Chromecast fix: MetricsStateManager segfaults if callbacks are empty.

chromecast/metrics/cast_metrics_unittest.cc

+// Copyright 2014 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/memory/scoped_ptr.h"
+#include "base/message_loop/message_loop.h"
+#include "base/prefs/testing_pref_service.h"
+#include "chromecast/metrics/cast_metrics_service_client.h"

[Alexei Svitkine (slow), 2014/08/29 17:58:29]

Nit: Chromium convention is now for this to be the first include followed by an
empty line.

[gunsch, 2014/08/29 18:26:05]

Done.

[gunsch, 2014/08/29 18:26:47]

Actually, had to put this back. It seems for unit tests, the presubmit check
still enforces these are all alphabetical.

[Alexei Svitkine (slow), 2014/08/29 18:43:15]

Odd. Which presubmit?

It certainly doesn't for other parts of the codebase:

https://code.google.com/p/chromium/codesearch#chromium/src/components/metrics...

Per the C++ style:

In dir/foo.cc or dir/foo_test.cc, whose main purpose is to implement or test the
stuff in dir2/foo2.h, order your includes as follows:

dir2/foo2.h (preferred location — see details below).
C system files.
C++ system files.
Other libraries' .h files.
Your project's .h files.

So if a presubmit is flagging those, we should file a bug against it. (Don't
block landing this change on it, just want to make sure the issue isn't
ignored.)

+#include "components/metrics/metrics_service.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace chromecast {
+
+class CastMetricsTest : public testing::Test {
+ protected:
+  virtual void SetUp() OVERRIDE {
+    message_loop_.reset(new base::MessageLoop());
+    prefs_.reset(new TestingPrefServiceSimple());
+    ::metrics::MetricsService::RegisterPrefs(prefs_->registry());
+  }
+
+  virtual void TearDown() OVERRIDE {
+  }
+

[Alexei Svitkine (slow), 2014/08/29 17:58:29]

Nit: Not sure you need to override this.

[gunsch, 2014/08/29 18:26:04]

Done.

+  scoped_ptr<base::MessageLoop> message_loop_;

[Alexei Svitkine (slow), 2014/08/29 17:58:29]

Nit: Put a private: section above these and add DISALLOW_COPY_AND_ASSIGN().

[gunsch, 2014/08/29 18:26:05]

Done.

+  scoped_ptr<TestingPrefServiceSimple> prefs_;
+};
+
+TEST_F(CastMetricsTest, CreateMetricsServiceClient) {
+  // Create and expect this to not crash.
+  metrics::CastMetricsServiceClient::Create(prefs_.get(), NULL);
+}
+
+}  // namespace chromecast