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

blimp/client/session/blimp_client_session_android.cc

Index: blimp/client/session/blimp_client_session_android.cc
diff --git a/blimp/client/session/blimp_client_session_android.cc b/blimp/client/session/blimp_client_session_android.cc
index a33e54af8aee2eeed7a2b7ca4368b66817fc0756..3a644953c7c4d41ac603827e6b4acc53ad059d89 100644
--- a/blimp/client/session/blimp_client_session_android.cc
+++ b/blimp/client/session/blimp_client_session_android.cc
@@ -7,6 +7,7 @@
 #include "jni/BlimpClientSession_jni.h"
 
 namespace blimp {
+namespace client {
 
 static jlong Init(JNIEnv* env, const JavaParamRef<jobject>& jobj) {
   return reinterpret_cast<intptr_t>(new BlimpClientSessionAndroid(env, jobj));
@@ -39,4 +40,5 @@ void BlimpClientSessionAndroid::Destroy(JNIEnv* env,
   delete this;
 }
 
+}  // namespace client
 }  // namespace blimp