Local NTP, Realbox: fix Shift+Enter opening 2 windows

Fixed: 1013832
Change-Id: I5563e500d7c5371fb61ce07b1336e9e5446cd052
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1857785
Auto-Submit: Dan Beam <dbeam@chromium.org>
Reviewed-by: Moe Ahmadi <mahmadi@chromium.org>
Commit-Queue: Dan Beam <dbeam@chromium.org>
Cr-Commit-Position: refs/heads/master@{#705720}

chrome/browser/resources/local_ntp/local_ntp.js

@@ -1269,6 +1269,7 @@ function onRealboxKeyDown(e) {
       // this forwards key modifiers. This enables Shift+Enter to open a match
       // in a new window, for example.
       matchEls[selected].dispatchEvent(new MouseEvent('click', e));
+      e.preventDefault();
     }
     return;
   }

chrome/test/data/local_ntp/realbox_browsertest.js

@@ -623,3 +623,30 @@ test.realbox.testRemoveIcon = function() {
 
   assertEquals(0, $(test.realbox.IDS.REALBOX_MATCHES).children.length);
 };
+
+test.realbox.testPressEnterOnResult = function() {
+  test.realbox.realboxEl.value = 'hello world';
+  test.realbox.realboxEl.dispatchEvent(new CustomEvent('input'));
+
+  const matches = [test.realbox.getSearchMatch({supportsDeletion: true})];
+  chrome.embeddedSearch.searchBox.onqueryautocompletedone(
+      {input: test.realbox.realboxEl.value, matches});
+
+  const matchEls = $(test.realbox.IDS.REALBOX_MATCHES).children;
+  assertEquals(1, matchEls.length);
+
+  let clicked = false;
+  matchEls[0].onclick = () => clicked = true;
+
+  const shiftEnter = new KeyboardEvent('keydown', {
+    bubbles: true,
+    cancelable: true,
+    key: 'Enter',
+    target: matchEls[0],
+    shiftKey: true,
+  });
+  test.realbox.realboxEl.dispatchEvent(shiftEnter);
+  assertTrue(shiftEnter.defaultPrevented);
+
+  assertTrue(clicked);
+};