Implement removing suggestions from clipboard

There are 3 parts to make "removing suggestions from clipboard" works.
1. when create Match In ClipboardProvider, set |deletable| to true.
This part makes long-press on the match can pop up delete dialog.
2. delete the match from matches in ClipboardProvider
This part will remove the suggestion from suggestion list.
3. delete the suggestion from system clipboard.

Bug: 998932
Change-Id: I5c55f1de6fe80e5f40f1181c504a4b1e536b4ec5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1775439
Commit-Queue: Gang Wu <[email protected]>
Reviewed-by: Ted Choc <[email protected]>
Reviewed-by: Justin Donnelly <[email protected]>
Reviewed-by: Olivier Robin <[email protected]>
Cr-Commit-Position: refs/heads/master@{#699617}
diff --git a/components/omnibox/common/omnibox_features.h b/components/omnibox/common/omnibox_features.h
index 4910578..028d931c 100644
--- a/components/omnibox/common/omnibox_features.h
+++ b/components/omnibox/common/omnibox_features.h
@@ -46,6 +46,7 @@
 extern const base::Feature kOmniboxMaterialDesignWeatherIcons;
 extern const base::Feature kOmniboxDisableInstantExtendedLimit;
 extern const base::Feature kOmniboxSearchEngineLogo;
+extern const base::Feature kOmniboxRemoveSuggestionsFromClipboard;
 
 // Flags that affect the "twiddle" step of AutocompleteResult, i.e. SortAndCull.
 // TODO(tommycli): There are more flags above that belong in this category.