Generate all extension schema namespaces as "api" and instead vary the generated bundle names.

extensions/common/api/cast_channel/logging.proto

 // Copyright 2014 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.
 
 syntax = "proto2";
 
 option optimize_for = LITE_RUNTIME;
 
-package extensions.core_api.cast_channel.proto;
+package extensions.api.cast_channel.proto;
 
 enum EventType {
   EVENT_TYPE_UNKNOWN = 0;
   CAST_SOCKET_CREATED = 1;
   READY_STATE_CHANGED = 2;
   CONNECTION_STATE_CHANGED = 3;
   READ_STATE_CHANGED = 4;
   WRITE_STATE_CHANGED = 5;
   ERROR_STATE_CHANGED = 6;
   CONNECT_FAILED = 7;
@@ skipping 126 matching lines @@
 message Log {
   // Each AggregatedSocketEvent represents events recorded for a socket.
   repeated AggregatedSocketEvent aggregated_socket_event = 1;
 
   // Number of socket log entries evicted by the logger due to size constraints.
   optional int32 num_evicted_aggregated_socket_events = 2;
 
   // Number of event log entries evicted by the logger due to size constraints.
   optional int32 num_evicted_socket_events = 3;
 }