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

blimp/client/session/tab_control_feature_android.h

Index: blimp/client/session/tab_control_feature_android.h
diff --git a/blimp/client/session/tab_control_feature_android.h b/blimp/client/session/tab_control_feature_android.h
index a7f4b5a46425cb96f9354327dec7b0bba6b21999..9cadcecc0fcb9fa3c1c82bf4ddfd709acd2aecde 100644
--- a/blimp/client/session/tab_control_feature_android.h
+++ b/blimp/client/session/tab_control_feature_android.h
@@ -9,6 +9,7 @@
 #include "base/macros.h"
 
 namespace blimp {
+namespace client {
 
 class TabControlFeature;
 
@@ -40,6 +41,7 @@ class TabControlFeatureAndroid {
   DISALLOW_COPY_AND_ASSIGN(TabControlFeatureAndroid);
 };
 
+}  // namespace client
 }  // namespace blimp
 
 #endif  // BLIMP_CLIENT_SESSION_TAB_CONTROL_FEATURE_ANDROID_H_