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

extensions/browser/api/cast_channel/cast_framer_unittest.cc

Index: extensions/browser/api/cast_channel/cast_framer_unittest.cc
diff --git a/extensions/browser/api/cast_channel/cast_framer_unittest.cc b/extensions/browser/api/cast_channel/cast_framer_unittest.cc
index c45bd319a75c98e1b4925d160df94de7b350e815..7abc580bc07ee1a8b5a6c49170200b054cc7cf14 100644
--- a/extensions/browser/api/cast_channel/cast_framer_unittest.cc
+++ b/extensions/browser/api/cast_channel/cast_framer_unittest.cc
@@ -11,7 +11,7 @@
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace extensions {
-namespace core_api {
+namespace api {
 namespace cast_channel {
 class CastFramerTest : public testing::Test {
  public:
@@ -134,5 +134,5 @@ TEST_F(CastFramerTest, TestUnparsableBodyProto) {
   EXPECT_EQ(cast_channel::CHANNEL_ERROR_INVALID_MESSAGE, error);
 }
 }  // namespace cast_channel
-}  // namespace core_api
+}  // namespace api
 }  // namespace extensions