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

extensions/browser/api/cast_channel/cast_framer_unittest.cc

 // 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.
 
 #include "extensions/browser/api/cast_channel/cast_framer.h"
 
 #include <algorithm>
 #include <string>
 
 #include "extensions/common/api/cast_channel/cast_channel.pb.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace extensions {
-namespace core_api {
+namespace api {
 namespace cast_channel {
 class CastFramerTest : public testing::Test {
  public:
   CastFramerTest() {}
   ~CastFramerTest() override {}
 
   void SetUp() override {
     cast_message_.set_protocol_version(CastMessage::CASTV2_1_0);
     cast_message_.set_source_id("source");
     cast_message_.set_destination_id("destination");
@@ skipping 102 matching lines @@
   EXPECT_EQ(cast_channel::CHANNEL_ERROR_NONE, error);
   EXPECT_EQ(cast_message_str_.size() - 4, framer_->BytesRequested());
 
   // Send body, expect an error.
   scoped_ptr<CastMessage> message;
   EXPECT_EQ(nullptr, framer_->Ingest(framer_->BytesRequested(), &message_length,
                                      &error).get());
   EXPECT_EQ(cast_channel::CHANNEL_ERROR_INVALID_MESSAGE, error);
 }
 }  // namespace cast_channel
-}  // namespace core_api
+}  // namespace api
 }  // namespace extensions