Simplify/Cleanup MediaClient

chrome/renderer/media/chrome_key_systems_provider.h

+// Copyright 2017 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.
+
+#ifndef CHROME_RENDERER_MEDIA_CHROME_KEY_SYSTEMS_PROVIDER_H_
+#define CHROME_RENDERER_MEDIA_CHROME_KEY_SYSTEMS_PROVIDER_H_
+
+#include <memory>
+#include <vector>
+
+#include "base/threading/thread_checker.h"
+#include "base/time/tick_clock.h"
+#include "base/time/time.h"
+#include "media/base/key_system_properties.h"
+
+namespace chrome {

[jochen (gone - plz use gerrit), 2017/04/06 13:00:05]

it's not really common to use namespace chrome unless there's a naming clash
with e.g. content or so

[chcunningham, 2017/04/06 20:48:34]

I noticed that in a number of files - whats the history there? 

I've seen a quite a few now have the chrome namespace (perhaps due to conflicts)
- are you wanting me to remove the namespace here?

+
+class TestKeySystemsProviderDelegate {

[jochen (gone - plz use gerrit), 2017/04/06 13:00:05]

Is that a testing delegate? In that case, I'd expect it to be in a different
file

[chcunningham, 2017/04/06 20:48:34]

I've replaced this interface with a simple callback. The callback is bound only
in the unit test file.

+ public:
+  virtual ~TestKeySystemsProviderDelegate() = default;
+  virtual void AddTestKeySystems(

[jochen (gone - plz use gerrit), 2017/04/06 13:00:05]

please add comments what this is supposed to do

[chcunningham, 2017/04/06 20:48:34]

N/A given new changes. I do have some comments above the test_provider_ member
to help readers. 

+      std::vector<std::unique_ptr<media::KeySystemProperties>>*
+          key_systems) = 0;
+};
+
+class ChromeKeySystemsProvider {
+ public:
+  ChromeKeySystemsProvider();
+  ~ChromeKeySystemsProvider();
+
+  // Adds properties for supported key systems.
+  void AddSupportedKeySystems(
+      std::vector<std::unique_ptr<media::KeySystemProperties>>* key_systems);
+
+  // Returns whether client key systems properties should be updated.
+  // TODO(chcunningham): Refactor this to a proper change "observer" API that is
+  // less fragile (don't assume AddSupportedKeySystems has just one caller).
+  bool IsKeySystemsUpdateNeeded();
+
+  void SetTickClockForTesting(std::unique_ptr<base::TickClock> tick_clock);
+  void SetProviderDelegateForTesting(
+      std::unique_ptr<TestKeySystemsProviderDelegate> test_provider);
+
+ private:
+  // Whether AddSupportedKeySystems() has ever been called.
+  bool has_updated_;
+
+  // Whether a future update is needed. For example, when some potentially
+  // supported key systems are NOT supported yet. This could happen when the
+  // required component for a key system is not yet available.
+  bool is_update_needed_;
+
+  // Throttle how often we signal an update is needed to avoid unnecessary high
+  // frequency of expensive IPC calls.
+  base::TimeTicks last_update_time_ticks_;
+  std::unique_ptr<base::TickClock> tick_clock_;
+
+  // Ensure all methods are called from the same (Main) thread.
+  base::ThreadChecker thread_checker_;
+
+  // For unit tests to inject their own key systems. Will bypass adding default
+  // Chrome key systems when set.
+  std::unique_ptr<TestKeySystemsProviderDelegate> test_provider_;
+
+  DISALLOW_COPY_AND_ASSIGN(ChromeKeySystemsProvider);
+};
+
+}  // namespace chrome
+
+#endif  // CHROME_RENDERER_MEDIA_CHROME_KEY_SYSTEMS_PROVIDER_H_