Remove explicit marker from ProcessMap.

Older gcc versions apparently do not support this when used with STL.

Review URL: http://codereview.chromium.org/8771061

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@113451 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/extensions/process_map.cc

@@ -11,7 +11,9 @@ struct ProcessMap::Item {
   Item() {
   }
 
-  explicit Item(const ProcessMap::Item& other)
+  // Purposely implicit constructor needed on older gcc's. See:
+  // http://codereview.chromium.org/8769022/
+  Item(const ProcessMap::Item& other)
       : extension_id(other.extension_id),
         process_id(other.process_id),
         site_instance_id(other.site_instance_id) {