[Chromoting] Add a filter that will stop the host sending unnecessary clipboard events to the clien…

remoting/protocol/clipboard_duplicate_filter.cc

+#include "remoting/protocol/clipboard_duplicate_filter.h"
+
+#include "remoting/proto/event.pb.h"
+
+namespace remoting {
+namespace protocol {
+
+ClipboardDuplicateFilter::ClipboardDuplicateFilter()
+  : to_host_(NULL),
+    to_client_(NULL),
+    filter_to_client_(this),
+    filter_to_host_(this) {
+}
+
+void ClipboardDuplicateFilter::set_to_client(ClipboardStub* clipboard_stub) {
+  to_client_ = clipboard_stub;
+}
+
+void ClipboardDuplicateFilter::set_to_host(ClipboardStub* clipboard_stub) {
+  to_host_ = clipboard_stub;
+}
+
+ClipboardStub* ClipboardDuplicateFilter::get_filter_to_client() {
+  return &filter_to_client_;
+}
+
+ClipboardStub* ClipboardDuplicateFilter::get_filter_to_host() {
+  return &filter_to_host_;
+}
+
+void ClipboardDuplicateFilter::InjectClipboardEventToClient(
+    const ClipboardEvent& event) {
+  if (!to_client_) {
+    return;
+  }
+  if (event.mime_type() == recent_mime_type_ && event.data() == recent_data_) {
+    return;
+  }
+  to_client_->InjectClipboardEvent(event);
+  recent_mime_type_ = event.mime_type();
+  recent_data_ = event.data();
+}
+
+void ClipboardDuplicateFilter::InjectClipboardEventToHost(
+    const ClipboardEvent& event) {
+  recent_mime_type_ = event.mime_type();
+  recent_data_ = event.data();
+  if (to_host_) {
+    to_host_->InjectClipboardEvent(event);
+  }
+}
+
+ClipboardDuplicateFilter::FilterToClient::FilterToClient(
+    ClipboardDuplicateFilter* filter) : filter_(filter) {
+}
+
+void ClipboardDuplicateFilter::FilterToClient::InjectClipboardEvent(
+    const ClipboardEvent& event) {
+  filter_->InjectClipboardEventToClient(event);
+}
+
+ClipboardDuplicateFilter::FilterToHost::FilterToHost(
+    ClipboardDuplicateFilter* filter) : filter_(filter) {
+}
+
+void ClipboardDuplicateFilter::FilterToHost::InjectClipboardEvent(
+    const ClipboardEvent& event) {
+  filter_->InjectClipboardEventToHost(event);
+}
+
+}  // namespace protocol
+}  // namespace remoting