message text : clear the conversation from the conversation page

Change-Id: I86a3cad4c5b39abb77d4924e7ae1cb468af828f2
Tuleap: #1287

MessageTextPage.xaml

@@ -147,6 +147,9 @@
                 <Button x:Name="_deleteContact_"
                         Content="delete"
                         Click="_deleteContact__Click"/>
+                    <Button x:Name="_clearConversation_"
+                        Content="clear conversation"
+                        Click="_clearConversation__Click"/>
                 </StackPanel>
             </StackPanel>
 

MessageTextPage.xaml.cpp

@@ -190,3 +190,12 @@ void RingClientUWP::Views::MessageTextPage::_deleteContact__Click(Platform::Obje
     ContactsViewModel::instance->deleteContact(contact);
     SmartPanelItemsViewModel::instance->removeItem(item);
 }
+
+
+void RingClientUWP::Views::MessageTextPage::_clearConversation__Click(Platform::Object^ sender, Windows::UI::Xaml::RoutedEventArgs^ e)
+{
+    auto item = SmartPanelItemsViewModel::instance->_selectedItem;
+    auto contact = item->_contact;
+    contact->_conversation->_messages->Clear();
+    contact->saveConversationToFile();
+}

MessageTextPage.xaml.h

@@ -58,6 +58,7 @@ private:
     void OnSelectionChanged(Platform::Object ^sender, Windows::UI::Xaml::Controls::SelectionChangedEventArgs ^e);
 
     void _deleteContact__Click(Platform::Object^ sender, Windows::UI::Xaml::RoutedEventArgs^ e);
+    void _clearConversation__Click(Platform::Object^ sender, Windows::UI::Xaml::RoutedEventArgs^ e);
 };
 }
 }