[omnibox bookmarks] Make short symbols match beginning of words

Currently, a symbol (that a user might enter in the Omnibox) that is
very short (e.g. 1 char) will not be allowed to match the beginning of
a word. This CL flips that match behavior to allow a partial match,
but only when a flag is set. We intend to measure and make sure that
suggestion quality doesn't degrade.

TBR: [email protected]
Bug: 925815
Change-Id: If279d0add5015a11d7528710a8cde020fba5cdef
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1488615
Reviewed-by: Kevin Bailey <[email protected]>
Reviewed-by: Justin Donnelly <[email protected]>
Reviewed-by: Scott Violet <[email protected]>
Commit-Queue: Kevin Bailey <[email protected]>
Cr-Commit-Position: refs/heads/master@{#656034}
diff --git a/components/omnibox/common/omnibox_features.cc b/components/omnibox/common/omnibox_features.cc
index 79adb02..5a053ff 100644
--- a/components/omnibox/common/omnibox_features.cc
+++ b/components/omnibox/common/omnibox_features.cc
@@ -78,6 +78,10 @@
 const base::Feature kOmniboxReverseAnswers{"OmniboxReverseAnswers",
                                            base::FEATURE_DISABLED_BY_DEFAULT};
 
+// Feature used to enable matching short words to bookmarks for suggestions.
+const base::Feature kOmniboxShortBookmarkSuggestions{
+    "OmniboxShortBookmarkSuggestions", base::FEATURE_DISABLED_BY_DEFAULT};
+
 // Feature used to force on the experiment of transmission of tail suggestions
 // from GWS to this client, currently testing for desktop.
 const base::Feature kOmniboxTailSuggestions{