Add a clear button to make it easier to replace the key

This way the current key can be easily whacked and replaced with
the user's desired key.

Signed-off-by: Shawn O. Pearce <sop@google.com>

src/main/java/com/google/gerrit/client/account/AccountConstants.java

@@ -34,6 +34,7 @@ public interface AccountConstants extends Constants {
   String tabAgreements();
 
   String buttonDeleteSshKey();
+  String buttonClearSshKeyInput();
   String buttonAddSshKey();
 
   String sshKeyInvalid();

src/main/java/com/google/gerrit/client/account/AccountConstants.properties

@@ -15,6 +15,7 @@ tabWebIdentities = Web Identities
 tabAgreements = Agreements
 
 buttonDeleteSshKey = Delete
+buttonClearSshKeyInput = Clear
 buttonAddSshKey = Add
 
 sshKeyInvalid = Invalid Key

src/main/java/com/google/gerrit/client/account/SshKeyPanel.java

@@ -42,6 +42,7 @@ import java.util.List;
 class SshKeyPanel extends Composite {
   private SshKeyTable keys;
 
+  private Button clearNew;
   private Button addNew;
   private TextArea addTxt;
   private Button delSel;
@@ -74,13 +75,25 @@ class SshKeyPanel extends Composite {
       addTxt.setCharacterWidth(80);
       fp.add(addTxt);
 
+      final FlowPanel buttons = new FlowPanel();
+      fp.add(buttons);
+
+      clearNew = new Button(Util.C.buttonClearSshKeyInput());
+      clearNew.addClickListener(new ClickListener() {
+        public void onClick(final Widget sender) {
+          addTxt.setText("");
+          addTxt.setFocus(true);
+        }
+      });
+      buttons.add(clearNew);
+
       addNew = new Button(Util.C.buttonAddSshKey());
       addNew.addClickListener(new ClickListener() {
         public void onClick(final Widget sender) {
           doAddNew();
         }
       });
-      fp.add(addNew);
+      buttons.add(addNew);
       body.add(fp);
     }