Fix "unreachable code" warnings (MSVC warning 4702) in content/.

content/common/indexed_db/indexed_db_param_traits.cc

Index: content/common/indexed_db/indexed_db_param_traits.cc
===================================================================
--- content/common/indexed_db/indexed_db_param_traits.cc	(revision 257821)
+++ content/common/indexed_db/indexed_db_param_traits.cc	(working copy)
@@ -105,8 +105,6 @@
       NOTREACHED();
       return false;
   }
-  NOTREACHED();
-  return false;
 }
 
 void ParamTraits<IndexedDBKey>::Log(const param_type& p, std::string* l) {
@@ -143,8 +141,10 @@
       return;
     case WebIDBKeyPathTypeNull:
       return;
+    default:
+      NOTREACHED();
+      return;
   }
-  NOTREACHED();
 }
 
 bool ParamTraits<IndexedDBKeyPath>::Read(const Message* m,
@@ -172,9 +172,10 @@
     case WebIDBKeyPathTypeNull:
       *r = IndexedDBKeyPath();
       return true;
+    default:
+      NOTREACHED();
+      return false;
   }
-  NOTREACHED();
-  return false;
 }
 
 void ParamTraits<IndexedDBKeyPath>::Log(const param_type& p, std::string* l) {