Add the supporting code for the cast system tray integration

ash/cast_config_delegate.h

Index: ash/cast_config_delegate.h
diff --git a/ash/cast_config_delegate.h b/ash/cast_config_delegate.h
new file mode 100644
index 0000000000000000000000000000000000000000..0b251f15d9c0ad6589dd31084c872ac579865899
--- /dev/null
+++ b/ash/cast_config_delegate.h
@@ -0,0 +1,87 @@
+// 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.
+
+#ifndef ASH_CAST_CONFIG_DELEGATE_H_
+#define ASH_CAST_CONFIG_DELEGATE_H_
+
+#include <map>
+#include <string>
+
+#include "ash/ash_export.h"
+#include "base/callback.h"
+#include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/strings/string16.h"
+#include "url/gurl.h"
+
+namespace ash {
+
+// This delegate allows the UI code in ash, e.g. |TrayCastDetailedView|,
+// to access the cast extension.
+class CastConfigDelegate {
+ public:
+  struct ASH_EXPORT Receiver {
+    Receiver();
+    ~Receiver();
+
+    std::string id;
+    base::string16 name;
+  };

[jennyz, 2015/05/07 21:50:34]

Add a blank line.

[jdufault, 2015/05/07 23:41:53]

Done.

+  struct ASH_EXPORT Activity {
+    // The tab identifier that we are casting. These are the special tab values
+    // taken from the chromecast extension itself. If an actual tab is being
+    // casted, then the TabId will be >= 0.
+    enum TabId {
+      EXTENSION = -1,
+      DESKTOP = -2,
+      DISCOVERED_ACTIVITY = -3,
+      EXTERNAL_EXTENSION_CLIENT = -4
+    };
+
+    Activity();
+    ~Activity();
+
+    std::string id;
+    base::string16 title;
+    std::string activity_type;
+    bool allow_stop = false;
+
+    // The id for the tab we are casting. Could be one of the TabId values,
+    // or a value >= 0 that represents that tab index of the tab we are
+    // casting. We default to casting the desktop, as a tab may not
+    // necessarily exist.
+    int tab_id = TabId::DESKTOP;

[jennyz, 2015/05/07 21:50:34]

How about initialize it in its constructor?

[jdufault, 2015/05/07 23:41:52]

Why?

[jennyz, 2015/05/08 18:01:15]

I typically looks into constructor for the default values of the class members.
Maybe this is just my preference. No big deal if you prefer the other way.

[achuithb, 2015/05/08 18:19:44]

This has also changed with C++11. We're now supposed to prefer in-class member
initialization to initialization in the ctor. Discussion is here:
https://groups.google.com/a/chromium.org/forum/#!topic/chromium-dev/zqB-DySA4V0

And the style guide recommends it here:
https://google-styleguide.googlecode.com/svn/trunk/cppguide.html#Initialization

The rationale is that with no ctor, or multiple ctors, there's a chance that
some variables could be left  uninitialized.

[jennyz, 2015/05/08 20:39:27]

Acknowledged.

+  };

[jennyz, 2015/05/07 21:50:34]

ditto

[jdufault, 2015/05/07 23:41:53]

Why?

[jennyz, 2015/05/08 18:01:15]

It looks neat between two structs. 

+  struct ASH_EXPORT ReceiverAndActivity {
+    ReceiverAndActivity();
+    ~ReceiverAndActivity();
+
+    Receiver receiver;
+    Activity activity;
+  };

[jennyz, 2015/05/07 21:50:35]

ditto

[jdufault, 2015/05/07 23:41:53]

Done.

+  using ReceiversAndActivites = std::map<std::string, ReceiverAndActivity>;

[jennyz, 2015/05/07 21:50:35]

Use typedef instead of using? Also, can you add a comment to explain what is the
key of the map?

[jdufault, 2015/05/07 23:41:52]

Done for comment.

Style guide says that using is preferred over typedef.

[jennyz, 2015/05/08 18:01:15]

Can you point me the Google or chromium c++ coding style guideline for this
recommendation?

[achuithb, 2015/05/08 18:12:19]

Jenny, using instead of a typedef for type alias is a new C++11 feature, and it
is preferred. Here's the discussion:
https://groups.google.com/a/chromium.org/forum/#!topic/chromium-dev/8dOAMzgR4ao

It's the first item in the list here:
https://chromium-cpp.appspot.com/

[jennyz, 2015/05/08 20:39:27]

Acknowledged.

+  using ReceiversAndActivitesCallback =
+      base::Callback<void(const ReceiversAndActivites&)>;

[jennyz, 2015/05/07 21:50:34]

typedef instead?

[jdufault, 2015/05/07 23:41:53]

See above.

+
+  virtual ~CastConfigDelegate();
+
+  // Returns true if cast extension is installed.
+  virtual bool HasCastExtension() = 0;
+  // Returns the list of cast receivers and activities.

[jennyz, 2015/05/07 21:50:35]

The function does not return list of the cast receives and activities. Please be
accurate to describe how they are passed with callback. See some examples in
this file:
https://code.google.com/p/chromium/codesearch#chromium/src/device/bluetooth/b...

[jdufault, 2015/05/07 23:41:53]

Done.

+  virtual void GetReceiversAndActivities(
+      const ReceiversAndActivitesCallback& callback) = 0;
+  // Cast to a device.

[jennyz, 2015/05/07 21:50:35]

Please explain what |receiver_id| specifies.

[jdufault, 2015/05/07 23:41:52]

Done.

+  virtual void CastToReceiver(const std::string& receiver_id) = 0;
+  // Stop ongoing cast.

[jennyz, 2015/05/07 21:50:34]

ditto.

[jdufault, 2015/05/07 23:41:53]

Done.

+  virtual void StopCasting(const std::string& activity_id) = 0;
+  // Opens Options page for cast.
+  virtual void LaunchCastOptions() = 0;
+
+ private:
+  DISALLOW_ASSIGN(CastConfigDelegate);
+};
+
+}  // namespace ash
+
+#endif  // ASH_CAST_CONFIG_DELEGATE_H_