Fix suggestion list not re-appearing when suggestions are unchanged.

This CL addresses the problem where AutocompleteController sends
unchanged list of suggestions to present.

Bug: 1082619
Change-Id: I78a7fb2652f45eafadb891720131b355a0649a6a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2202383
Commit-Queue: Ender <ender@google.com>
Reviewed-by: Ted Choc <tedchoc@chromium.org>
Auto-Submit: Ender <ender@google.com>
Cr-Commit-Position: refs/heads/master@{#768914}

chrome/android/java/src/org/chromium/chrome/browser/omnibox/suggestions/AutocompleteMediator.java

@@ -1266,6 +1266,7 @@ class AutocompleteMediator implements OnSuggestionsReceivedListener, StartStopWi
 
         getSuggestionModelList().clear();
         mViewInfoList.clear();
+        mAutocompleteResult = new AutocompleteResult(null, null);
         updateOmniboxSuggestionsVisibility();
     }
 

chrome/android/native_java_unittests/src/org/chromium/chrome/browser/omnibox/suggestions/AutocompleteMediatorUnitTest.java

@@ -559,6 +559,40 @@ public class AutocompleteMediatorUnitTest {
         verify(mAutocompleteDelegate, never()).setKeyboardVisibility(eq(false));
     }
 
+    @CalledByNativeJavaTest
+    @NativeJavaTestFeatures.Disable({ChromeFeatureList.OMNIBOX_ADAPTIVE_SUGGESTIONS_COUNT,
+            ChromeFeatureList.OMNIBOX_DEFERRED_KEYBOARD_POPUP})
+    public void
+    updateSuggestionsList_suggestionsAreRebuiltOnSubsequentInteractions() {
+        // This test validates scenario:
+        // 1. user focuses omnibox
+        // 2. AutocompleteMediator receives suggestions
+        // 3. user sees suggestions, but leaves omnibox
+        // 4. user focuses omnibox again
+        // 5. AutocompleteMediator receives same suggestions as in (2)
+        // 6. user sees suggestions again.
+        final List<OmniboxSuggestion> res1 = buildDummySuggestionsList(10, "Suggestion");
+        final List<OmniboxSuggestion> res2 = buildDummySuggestionsList(10, "Suggestion");
+        Assert.assertEquals(res1, res2);
+
+        mMediator.onNativeInitialized();
+        mMediator.onSuggestionsReceived(new AutocompleteResult(res1, null), "");
+        Assert.assertEquals(mMediator.getSuggestionViewInfoListForTest().size(), res1.size());
+        Assert.assertTrue(mListModel.get(SuggestionListProperties.VISIBLE));
+
+        mMediator.onUrlFocusChange(false);
+        Assert.assertFalse(mListModel.get(SuggestionListProperties.VISIBLE));
+        Assert.assertEquals(mMediator.getSuggestionViewInfoListForTest().size(), 0);
+
+        // Simulate omnibox focused. this bypasses the native call to fetch suggestions.
+        mMediator.setSuggestionVisibilityState(
+                AutocompleteMediator.SuggestionVisibilityState.ALLOWED);
+
+        mMediator.onSuggestionsReceived(new AutocompleteResult(res2, null), "");
+        Assert.assertEquals(mMediator.getSuggestionViewInfoListForTest().size(), res2.size());
+        Assert.assertTrue(mListModel.get(SuggestionListProperties.VISIBLE));
+    }
+
     @CalledByNativeJavaTest
     @NativeJavaTestFeatures.Disable({ChromeFeatureList.OMNIBOX_ADAPTIVE_SUGGESTIONS_COUNT,
             ChromeFeatureList.OMNIBOX_DEFERRED_KEYBOARD_POPUP})