Fix TabsInfo is null bug

TabsInfo can be null. It is best to transform
a null TabsInfo list to an empty list in the
constructor to avoid the consumer needing
to do null checks.

Bug: 1061991
Change-Id: If6345ed3bed720b783415b62a86bb8361ec5c2b0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2128566
Commit-Queue: David Maunder <davidjm@chromium.org>
Reviewed-by: Yusuf Ozuysal <yusufo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#756850}

chrome/android/features/tab_ui/java/src/org/chromium/chrome/browser/tasks/tab_management/suggestions/TabSuggestion.java

@@ -35,7 +35,8 @@ public final class TabSuggestion {
 
     public TabSuggestion(List<TabContext.TabInfo> tabsInfo, @TabSuggestionAction int action,
             String providerName, Integer tabGroupId) {
-        mTabsInfo = Collections.unmodifiableList(tabsInfo);
+        mTabsInfo =
+                tabsInfo == null ? Collections.emptyList() : Collections.unmodifiableList(tabsInfo);
         mAction = action;
         mProviderName = providerName;
         mTabGroupId = tabGroupId;

chrome/android/features/tab_ui/junit/src/org/chromium/chrome/browser/tasks/tab_management/suggestions/TabSuggestionTest.java

+// Copyright 2020 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.chrome.browser.tasks.tab_management.suggestions;
+
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.TestRule;
+import org.junit.runner.RunWith;
+import org.mockito.MockitoAnnotations;
+import org.robolectric.annotation.Config;
+
+import org.chromium.chrome.test.util.browser.Features;
+import org.chromium.testing.local.LocalRobolectricTestRunner;
+
+import java.util.Arrays;
+
+/**
+ * Tests functionality related to TabContext
+ */
+@RunWith(LocalRobolectricTestRunner.class)
+@Config(manifest = Config.NONE)
+public class TabSuggestionTest {
+    private static final @TabSuggestion.TabSuggestionAction int TAB_SUGGESTION_ACTION =
+            TabSuggestion.TabSuggestionAction.CLOSE;
+    private static final String PROVIDER_NAME = "providerName";
+    private static final int TAB_GROUP_ID = 1;
+    private static final int ID = 1;
+    private static final String TITLE = "title";
+    private static final String TAB_URL = "url";
+    private static final String ORIGINAL_URL = "original_url";
+    private static final String REFERRER_URL = "referrer_url";
+    private static final long TIMESTAMP = 4352345L;
+    private static final String VISIBLE_URL = "visible_url";
+    private static final TabContext.TabInfo TAB_INFO = new TabContext.TabInfo(
+            ID, TITLE, TAB_URL, ORIGINAL_URL, REFERRER_URL, TIMESTAMP, VISIBLE_URL);
+
+    @Rule
+    public TestRule mProcessor = new Features.JUnitProcessor();
+
+    @Before
+    public void setUp() {
+        MockitoAnnotations.initMocks(this);
+    }
+
+    @Test
+    public void testNonEmptySuggestions() {
+        TabSuggestion tabSuggestion = new TabSuggestion(
+                Arrays.asList(TAB_INFO), TAB_SUGGESTION_ACTION, PROVIDER_NAME, TAB_GROUP_ID);
+        Assert.assertNotNull(tabSuggestion.getTabsInfo());
+        Assert.assertEquals(tabSuggestion.getTabsInfo().size(), 1);
+        Assert.assertEquals(tabSuggestion.getTabsInfo().get(0), TAB_INFO);
+    }
+
+    @Test
+    public void testNullSuggestions() {
+        TabSuggestion tabSuggestion =
+                new TabSuggestion(null, TAB_SUGGESTION_ACTION, PROVIDER_NAME, TAB_GROUP_ID);
+        Assert.assertNotNull(tabSuggestion.getTabsInfo());
+        Assert.assertEquals(tabSuggestion.getTabsInfo().size(), 0);
+    }
+}

chrome/android/features/tab_ui/tab_management_java_sources.gni

@@ -77,6 +77,7 @@ tab_management_junit_java_sources = [
   "//chrome/android/features/tab_ui/junit/src/org/chromium/chrome/browser/tasks/tab_management/suggestions/StaleTabSuggestionProviderTest.java",
   "//chrome/android/features/tab_ui/junit/src/org/chromium/chrome/browser/tasks/tab_management/suggestions/TabContextObserverTest.java",
   "//chrome/android/features/tab_ui/junit/src/org/chromium/chrome/browser/tasks/tab_management/suggestions/TabContextTest.java",
+  "//chrome/android/features/tab_ui/junit/src/org/chromium/chrome/browser/tasks/tab_management/suggestions/TabSuggestionTest.java",
   "//chrome/android/features/tab_ui/junit/src/org/chromium/chrome/browser/tasks/tab_management/suggestions/TabSuggestionsClientFetcherTest.java",
   "//chrome/android/features/tab_ui/junit/src/org/chromium/chrome/browser/tasks/tab_management/suggestions/TabSuggestionsOrchestratorTest.java",
 ]