[SendTabToSelf] Null navigation_time valid in link flow

When the shared url is derived from a link, and the page hasnt been
opened yet, there is no Navigation Entry. and therefore no
navigation_time

Bug: 947617
Change-Id: I6e8964c48cd0db7778fa73b898793200a29a3f45
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1546143
Commit-Queue: Jeffrey Cohen <jeffreycohen@chromium.org>
Reviewed-by: Sebastien Seguin-Gagnon <sebsg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#646957}

components/send_tab_to_self/send_tab_to_self_bridge.cc

@@ -247,11 +247,6 @@ const SendTabToSelfEntry* SendTabToSelfBridge::AddEntry(
     return nullptr;
   }
 
-  if (navigation_time.is_null()) {
-    UMA_HISTOGRAM_ENUMERATION(kAddEntryStatus, FAILURE);
-    return nullptr;
-  }
-
   if (!url.is_valid()) {
     UMA_HISTOGRAM_ENUMERATION(kAddEntryStatus, FAILURE);
     return nullptr;

components/send_tab_to_self/send_tab_to_self_bridge_unittest.cc

@@ -446,8 +446,9 @@ TEST_F(SendTabToSelfBridgeTest, AddInvalidEntries) {
   EXPECT_EQ(nullptr, bridge()->AddEntry(GURL("http//google.com"), "d",
                                         AdvanceAndGetTime(), "target_device"));
 
-  // Add Entry should fail on an invalid navigation_time.
-  EXPECT_EQ(nullptr, bridge()->AddEntry(GURL("http://www.example.com/"), "d",
+  // Add Entry should succeed on an invalid navigation_time, since that is the
+  // case for sending links.
+  EXPECT_NE(nullptr, bridge()->AddEntry(GURL("http://www.example.com/"), "d",
                                         base::Time(), "target_device"));
 }