Add an extension bubble explaining which extensions are in dev mode.

chrome/browser/extensions/extension_prefs.h

 // Copyright (c) 2012 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_BROWSER_EXTENSIONS_EXTENSION_PREFS_H_
 #define CHROME_BROWSER_EXTENSIONS_EXTENSION_PREFS_H_
 
 #include <set>
 #include <string>
 #include <vector>
@@ skipping 284 matching lines @@
   // Whether the external extension was installed during the first run
   // of this profile.
   bool IsExternalInstallFirstRun(const std::string& extension_id);
   void SetExternalInstallFirstRun(const std::string& extension_id);
 
   // Whether the user has been notified about extension with |extension_id|
   // being wiped out.
   bool HasWipeoutBeenAcknowledged(const std::string& extension_id);
   void SetWipeoutAcknowledged(const std::string& extension_id, bool value);
 
+  // Whether the user has been notified about extension with |extension_id|
+  // only running because of dev mode being on.
+  bool HasDevModeBeenAcknowledged(const std::string& extension_id);
+  void SetDevModeAcknowledged(const std::string& extension_id, bool value);

[not at google - send to devlin, 2013/12/04 17:25:13]

why are we storing this in preferences? Isn't the point of this that we don't
store such things in preferences, and we show it on every startup?

[Finnur, 2013/12/05 23:55:56]

Indeed. Done.

+
   // Returns true if the extension notification code has already run for the
   // first time for this profile. Currently we use this flag to mean that any
   // extensions that would trigger notifications should get silently
   // acknowledged. This is a fuse. Calling it the first time returns false.
   // Subsequent calls return true. It's not possible through an API to ever
   // reset it. Don't call it unless you mean it!
   bool SetAlertSystemFirstRun();
 
   // Checks if extensions are blacklisted by default, by policy.
   // The ManagementPolicy::Provider methods also take this into account, and
@@ skipping 338 matching lines @@
   scoped_ptr<TimeProvider> time_provider_;
 
   bool extensions_disabled_;
 
   DISALLOW_COPY_AND_ASSIGN(ExtensionPrefs);
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_PREFS_H_