Use Google as a fallback Answer icon.

It appears that we have a non-trivial number of answer suggestions
that are either of invalid, or unspecified type.
We have been largely unaware of this situation since the original
code used value of 0 to mark an unspecified suggestion type; this
value has never beed handled by PropertyModel, since the implicit
value for int property is 0 (ergo no update detected).

In current model we explicitly determine decoration type at the time
suggestion is processed and prepare suggestion drawable instead.

Bug: 1016236
Change-Id: I83800041f563bf18e2a918b7e405af8ce84910f4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1873878Reviewed-by: Theresa  <twellington@chromium.org>
Commit-Queue: Ender <ender@google.com>
Cr-Commit-Position: refs/heads/master@{#708380}

chrome/android/java/src/org/chromium/chrome/browser/omnibox/suggestions/answer/AnswerSuggestionProcessor.java

@@ -232,6 +232,6 @@ public class AnswerSuggestionProcessor extends BaseSuggestionViewProcessor {
             assert suggestion.getType() == OmniboxSuggestionType.CALCULATOR;
             return R.drawable.ic_equals_sign_round;
         }
-        return 0;
+        return R.drawable.ic_google_round;
     }
 }