Allow input & clipboard filters to be disabled without NULLing target stub.

remoting/protocol/clipboard_filter.cc

Index: remoting/protocol/clipboard_filter.cc
diff --git a/remoting/protocol/clipboard_filter.cc b/remoting/protocol/clipboard_filter.cc
index 4b4be959d3af52ff77ec414f84b12adfb033cd0d..d82547f8971316217ea4b5fbfd474a3104d2757c 100644
--- a/remoting/protocol/clipboard_filter.cc
+++ b/remoting/protocol/clipboard_filter.cc
@@ -8,7 +8,11 @@
 namespace remoting {
 namespace protocol {
 
-ClipboardFilter::ClipboardFilter() : clipboard_stub_(NULL) {
+ClipboardFilter::ClipboardFilter() : clipboard_stub_(NULL), enabled_(true) {
+}
+
+ClipboardFilter::ClipboardFilter(ClipboardStub* clipboard_stub)
+    : clipboard_stub_(clipboard_stub), enabled_(true) {
 }
 
 ClipboardFilter::~ClipboardFilter() {
@@ -19,7 +23,7 @@ void ClipboardFilter::set_clipboard_stub(ClipboardStub* clipboard_stub) {
 }
 
 void ClipboardFilter::InjectClipboardEvent(const ClipboardEvent& event) {
-  if (clipboard_stub_ != NULL)
+  if (enabled_ && clipboard_stub_ != NULL)
     clipboard_stub_->InjectClipboardEvent(event);
 }