Introduce HostID and de-couple Extensions from "script injection System" [browser side]

extensions/common/consumer.h

Index: extensions/common/consumer.h
diff --git a/extensions/common/consumer.h b/extensions/common/consumer.h
new file mode 100644
index 0000000000000000000000000000000000000000..b7ea0c15cebbf95be73273fab3ab9b0de64936b8
--- /dev/null
+++ b/extensions/common/consumer.h
@@ -0,0 +1,73 @@
+// 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 EXTENSIONS_COMMON_CONSUMER_H_

[Devlin, 2015/01/20 17:51:06]

Given the contents of this file, I think it makes more sense to have it be
consumer_id.h/.cc.

In case you haven't discovered it:
~   $ cd <SOURCE_DIR>
src $ ./tools/git/move_source_file.py extensions/common/consumer.h
extensions/common/consumer_id.h
src $ ./tools/git/move_source_file.py extensions/common/consumer_id.cc
extensions/common/consumer_id.cc

That will update all dependents of the file, including the gypis.  Might wanna
check the gns;  I'm not sure the script was updated for those yet.

[Xi Han, 2015/01/21 21:30:17]

This git tool really handy for refactoring, thanks.

+#define EXTENSIONS_COMMON_CONSUMER_H_
+
+#include <string>
+
+#include "base/macros.h"
+
+// IDs of API consumers who own user scripts.
+// A ConsumerID is immutable after creation.
+// A ConsumerID could be used for an extension, a <webview> created by an
+// extension, or a <webview> created by WebUI.
+class ConsumerID {
+ public:
+  // The type of a host who contains regular tabs or <webview>s.
+  enum HostType { EXTENSIONS, WEBUI };
+
+  enum InstanceType { TAB, WEBVIEW };
+
+  // Default instance ID of a consumer who owns statically defined user scripts.
+  static const int kDefaultInstanceID;
+
+  ConsumerID();
+  explicit ConsumerID(const ConsumerID& other);

[Devlin, 2015/01/20 17:51:06]

Make a note here about why we allow copying/why it's okay.

[Xi Han, 2015/01/21 21:30:17]

It seems we don't need this copy constructor now, removed.

+  ConsumerID(HostType host_type,
+             const std::string& host_id,
+             InstanceType instance_type,
+             int instance_id);

[Devlin, 2015/01/20 17:51:06]

I think I'd slightly prefer an "is_declarative" bool here, and then removing the
public access to kDefaultInstanceID and GetNextID, since they are implementation
details.

[Xi Han, 2015/01/21 21:30:17]

That is a good point. I won't add the is_declarative in this constructor, since
is_declarative is used to hide the details of assignment for instance_id, and it
doesn't make sense that we have both instance_id and is_declarative. Instead, I
will create another constructor without instance_id but with is_declarative.

+  ~ConsumerID();
+
+  // Get next available instance ID.
+  static int GetNextID();
+
+  bool operator<(const ConsumerID& id) const;
+  void operator=(const ConsumerID& id);
+
+  HostType host_type() const { return host_type_; }
+  const std::string& host_id() const { return host_id_; }
+  InstanceType instance_type() const { return instance_type_; }
+  int instance_id() const { return instance_id_; }
+
+ private:
+  // Extension or WebUI.

[Devlin, 2015/01/20 17:51:06]

nit: Just say "The host type of the consumer." The enum already says that this
is either extension or webui, and there's no point in needing to update this
comment, too, when we add host type FluxCapacitor. :)

[Xi Han, 2015/01/21 21:30:17]

Done.

+  HostType host_type_;
+
+  // Similar to extension_id, host_id is a unique indentifier for a host,
+  // e.g., an Extension or WebUI.
+  std::string host_id_;
+
+  // A tab or a <webiew>.
+  InstanceType instance_type_;

[Devlin, 2015/01/20 17:51:06]

Similar comment to above.

[Xi Han, 2015/01/21 21:30:17]

Done.

+
+  // For a consumer that owns staticlly defined user scripts, the
+  // |instance_id| is 0;

[Devlin, 2015/01/20 17:51:06]

nit: either make the semicolon a period, or fix wrapping and capitalization.

[Xi Han, 2015/01/21 21:30:17]

Replace the semicolon with a period:)

+  // For a consumer that owns declarative user scripts, the |instance_id|
+  // is assigned by DeclarativeUserScriptManager when the consumer requests a
+  // master object.
+  int instance_id_;
+};
+
+// Represents an API consumer.
+class Consumer {

[Devlin, 2015/01/20 17:51:06]

When is this used?

[Xi Han, 2015/01/21 21:30:17]

It is not used in this patch, I can just remove it for now.

+ public:
+  Consumer();
+  virtual ~Consumer();
+
+  DISALLOW_COPY_AND_ASSIGN(Consumer);
+};
+
+#endif  // EXTENSIONS_COMMON_CONSUMER_H_