[Blimp client] Move client code into blimp::client namespace

blimp/client/session/blimp_client_session.h

Index: blimp/client/session/blimp_client_session.h
diff --git a/blimp/client/session/blimp_client_session.h b/blimp/client/session/blimp_client_session.h
index 8c3ca14dd9f36e554a7ad63e3c23dc88d5e20090..e9b7db0825130b1e8d25d0f8ba2eb5a1b3f7200a 100644
--- a/blimp/client/session/blimp_client_session.h
+++ b/blimp/client/session/blimp_client_session.h
@@ -19,6 +19,9 @@ class BlimpMessageProcessor;
 class BlimpMessageThreadPipe;
 class BrowserConnectionHandler;
 class ClientConnectionManager;
+
+namespace client {
+
 class ClientNetworkComponents;
 class NavigationFeature;
 class RenderWidgetFeature;
@@ -68,6 +71,7 @@ class BLIMP_CLIENT_EXPORT BlimpClientSession {
   DISALLOW_COPY_AND_ASSIGN(BlimpClientSession);
 };
 
+}  // namespace client
 }  // namespace blimp
 
 #endif  // BLIMP_CLIENT_SESSION_BLIMP_CLIENT_SESSION_H_