[omnibox] Increase max classifications text length.

Before the classification deduping changes, some providers limited the
texts to 200 characters when classifying. When either the suggestion or
input texts were longer, truncated versions would be used instead. With
the classification deduping changes, all providers follow this behavior.

This can look slightly awkward; e.g. for an input of 220 characters, the
search-what-you-typed suggestion will be un-bolded for the first 200
characters, but bolded for the last 20.

This CL increases the truncation length from 200 to 2000. This should be
large enough to cover most use cases; on a 3840 resolution screen, with
default English fonts, approximately 1100 '|'s fit in the omnibox.

Bug: 366623, 968911
Change-Id: Ic4648c3fa000c09563fe0afae0d4883cefe3d156
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1639105Reviewed-by: Tommy Li <tommycli@chromium.org>
Commit-Queue: manuk hovanesian <manukh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#665296}

components/omnibox/browser/autocomplete_match_classification.cc

@@ -11,7 +11,7 @@
 namespace {
 
 base::string16 clean(base::string16 text) {
-  const size_t kMaxTextLength = 200;
+  const size_t kMaxTextLength = 2000;
   return base::i18n::ToLower(text.substr(0, kMaxTextLength));
 }