Ruby wrapping of core credentials API change.
diff --git a/src/ruby/bin/apis/pubsub_demo.rb b/src/ruby/bin/apis/pubsub_demo.rb
index a039d03..003e91a 100755
--- a/src/ruby/bin/apis/pubsub_demo.rb
+++ b/src/ruby/bin/apis/pubsub_demo.rb
@@ -66,7 +66,7 @@
 
 # creates a SSL Credentials from the production certificates.
 def ssl_creds
-  GRPC::Core::Credentials.new(load_prod_cert)
+  GRPC::Core::ChannelCredentials.new(load_prod_cert)
 end
 
 # Builds the metadata authentication update proc.
diff --git a/src/ruby/bin/math_client.rb b/src/ruby/bin/math_client.rb
index 0ebd26f..d7e00e4 100755
--- a/src/ruby/bin/math_client.rb
+++ b/src/ruby/bin/math_client.rb
@@ -102,7 +102,7 @@
 
 def test_creds
   certs = load_test_certs
-  GRPC::Core::Credentials.new(certs[0])
+  GRPC::Core::ChannelCredentials.new(certs[0])
 end
 
 def main
diff --git a/src/ruby/bin/noproto_client.rb b/src/ruby/bin/noproto_client.rb
index 390a9c5..3aa1187 100755
--- a/src/ruby/bin/noproto_client.rb
+++ b/src/ruby/bin/noproto_client.rb
@@ -68,7 +68,7 @@
 
 def test_creds
   certs = load_test_certs
-  GRPC::Core::Credentials.new(certs[0])
+  GRPC::Core::ChannelCredentials.new(certs[0])
 end
 
 def main
diff --git a/src/ruby/lib/grpc/generic/client_stub.rb b/src/ruby/lib/grpc/generic/client_stub.rb
index b8e33ad..90aaa02 100644
--- a/src/ruby/lib/grpc/generic/client_stub.rb
+++ b/src/ruby/lib/grpc/generic/client_stub.rb
@@ -51,7 +51,9 @@
       end
       kw['grpc.primary_user_agent'] = "grpc-ruby/#{VERSION}"
       return Core::Channel.new(host, kw) if creds.nil?
-      fail(TypeError, '!Credentials') unless creds.is_a?(Core::Credentials)
+      unless creds.is_a?(Core::ChannelCredentials)
+        fail(TypeError, '!ChannelCredentials')
+      end
       Core::Channel.new(host, kw, creds)
     end
 
@@ -106,7 +108,7 @@
     # @param q [Core::CompletionQueue] used to wait for events
     # @param channel_override [Core::Channel] a pre-created channel
     # @param timeout [Number] the default timeout to use in requests
-    # @param creds [Core::Credentials] the channel
+    # @param creds [Core::ChannelCredentials] the channel credentials
     # @param update_metadata a func that updates metadata as described above
     # @param kw [KeywordArgs]the channel arguments
     def initialize(host, q,
diff --git a/src/ruby/pb/test/client.rb b/src/ruby/pb/test/client.rb
index 164e304..800529f 100755
--- a/src/ruby/pb/test/client.rb
+++ b/src/ruby/pb/test/client.rb
@@ -86,13 +86,13 @@
 # creates SSL Credentials from the test certificates.
 def test_creds
   certs = load_test_certs
-  GRPC::Core::Credentials.new(certs[0])
+  GRPC::Core::ChannelCredentials.new(certs[0])
 end
 
 # creates SSL Credentials from the production certificates.
 def prod_creds
   cert_text = load_prod_cert
-  GRPC::Core::Credentials.new(cert_text)
+  GRPC::Core::ChannelCredentials.new(cert_text)
 end
 
 # creates the SSL Credentials.
diff --git a/src/ruby/spec/credentials_spec.rb b/src/ruby/spec/channel_credentials_spec.rb
similarity index 78%
rename from src/ruby/spec/credentials_spec.rb
rename to src/ruby/spec/channel_credentials_spec.rb
index b02219d..b2bdf70 100644
--- a/src/ruby/spec/credentials_spec.rb
+++ b/src/ruby/spec/channel_credentials_spec.rb
@@ -29,8 +29,8 @@
 
 require 'grpc'
 
-describe GRPC::Core::Credentials do
-  Credentials = GRPC::Core::Credentials
+describe GRPC::Core::ChannelCredentials do
+  ChannelCredentials = GRPC::Core::ChannelCredentials
 
   def load_test_certs
     test_root = File.join(File.dirname(__FILE__), 'testdata')
@@ -40,32 +40,24 @@
 
   describe '#new' do
     it 'can be constructed with fake inputs' do
-      expect { Credentials.new('root_certs', 'key', 'cert') }.not_to raise_error
+      blk = proc  { ChannelCredentials.new('root_certs', 'key', 'cert') }
+      expect(&blk).not_to raise_error
     end
 
     it 'it can be constructed using specific test certificates' do
       certs = load_test_certs
-      expect { Credentials.new(*certs) }.not_to raise_error
+      expect { ChannelCredentials.new(*certs) }.not_to raise_error
     end
 
     it 'can be constructed with server roots certs only' do
       root_cert, _, _ = load_test_certs
-      expect { Credentials.new(root_cert) }.not_to raise_error
+      expect { ChannelCredentials.new(root_cert) }.not_to raise_error
     end
 
     it 'cannot be constructed with a nil server roots' do
       _, client_key, client_chain = load_test_certs
-      blk = proc { Credentials.new(nil, client_key, client_chain) }
+      blk = proc { ChannelCredentials.new(nil, client_key, client_chain) }
       expect(&blk).to raise_error
     end
   end
-
-  describe '#compose' do
-    it 'cannot be completed OK with 2 SSL creds' do
-      certs = load_test_certs
-      cred1 = Credentials.new(*certs)
-      cred2 = Credentials.new(*certs)
-      expect { cred1.compose(cred2) }.to raise_error
-    end
-  end
 end
diff --git a/src/ruby/spec/channel_spec.rb b/src/ruby/spec/channel_spec.rb
index 25cefcd..b4d2b94 100644
--- a/src/ruby/spec/channel_spec.rb
+++ b/src/ruby/spec/channel_spec.rb
@@ -40,7 +40,7 @@
   let(:cq) { GRPC::Core::CompletionQueue.new }
 
   def create_test_cert
-    GRPC::Core::Credentials.new(load_test_certs[0])
+    GRPC::Core::ChannelCredentials.new(load_test_certs[0])
   end
 
   shared_examples '#new' do
diff --git a/src/ruby/spec/client_server_spec.rb b/src/ruby/spec/client_server_spec.rb
index ad0fb26..734f176 100644
--- a/src/ruby/spec/client_server_spec.rb
+++ b/src/ruby/spec/client_server_spec.rb
@@ -431,7 +431,7 @@
     @server.start
     args = { Channel::SSL_TARGET => 'foo.test.google.fr' }
     @ch = Channel.new("0.0.0.0:#{server_port}", args,
-                      GRPC::Core::Credentials.new(certs[0], nil, nil))
+                      GRPC::Core::ChannelCredentials.new(certs[0], nil, nil))
   end
 
   after(:example) do
diff --git a/src/ruby/spec/generic/client_stub_spec.rb b/src/ruby/spec/generic/client_stub_spec.rb
index c5173ae..da5bc6c 100644
--- a/src/ruby/spec/generic/client_stub_spec.rb
+++ b/src/ruby/spec/generic/client_stub_spec.rb
@@ -113,7 +113,7 @@
         opts = {
           GRPC::Core::Channel::SSL_TARGET => 'foo.test.google.fr',
           a_channel_arg: 'an_arg',
-          creds: GRPC::Core::Credentials.new(certs[0], nil, nil)
+          creds: GRPC::Core::ChannelCredentials.new(certs[0], nil, nil)
         }
         GRPC::ClientStub.new(fake_host, @cq, **opts)
       end