Add offline_enabled field in manifest.

chrome/common/extensions/extension.h

Index: chrome/common/extensions/extension.h
diff --git a/chrome/common/extensions/extension.h b/chrome/common/extensions/extension.h
index d5801f53c0b270a6e61533bdc03f9dc5e695bb1c..79e58379553d73bc8f2f244db58a45e4dd345a22 100644
--- a/chrome/common/extensions/extension.h
+++ b/chrome/common/extensions/extension.h
@@ -532,6 +532,7 @@ class Extension : public base::RefCountedThreadSafe<Extension> {
   }
   const std::string omnibox_keyword() const { return omnibox_keyword_; }
   bool incognito_split_mode() const { return incognito_split_mode_; }
+  bool offline_enabled() const { return offline_enabled_; }
   const std::vector<TtsVoice>& tts_voices() const { return tts_voices_; }
 
   bool wants_file_access() const { return wants_file_access_; }
@@ -708,6 +709,9 @@ class Extension : public base::RefCountedThreadSafe<Extension> {
   // mode.
   bool incognito_split_mode_;
 
+  // Whether the extension or app should be enabled when offline.
+  bool offline_enabled_;
+
   // Defines the set of URLs in the extension's web content.
   URLPatternSet extent_;