Linux: implement Page Actions support.

chrome/browser/extensions/extensions_service.h

Index: chrome/browser/extensions/extensions_service.h
diff --git a/chrome/browser/extensions/extensions_service.h b/chrome/browser/extensions/extensions_service.h
index a17ef935c2c09d349b8b08b095c22d6ee1b38bbc..85822a16750dbb05895cbeebeb5b55f79cc62c19 100644
--- a/chrome/browser/extensions/extensions_service.h
+++ b/chrome/browser/extensions/extensions_service.h
@@ -102,6 +102,10 @@ class ExtensionsService
     return GetExtensionByIdInternal(id, true, false);
   }
 
+  // Retrieves a vector of all page actions, irrespective of which
+  // extension they belong to.
+  std::vector<PageAction*> GetPageActions() const;
+
   // Install the extension file at |extension_path|.  Will install as an
   // update if an older version is already installed.
   // For fresh installs, this method also causes the extension to be