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/chrome/browser/flag_descriptions.cc b/chrome/browser/flag_descriptions.cc
index 686c556..51fb902 100644
--- a/chrome/browser/flag_descriptions.cc
+++ b/chrome/browser/flag_descriptions.cc
@@ -1390,6 +1390,11 @@
     "Configures Omnibox on-focus suggestions - suggestions displayed on-focus "
     "before the user has typed any input";
 
+const char kOmniboxRemoveSuggestionsFromClipboardName[] =
+    "Omnibox remove suggestions from clipboard";
+const char kOmniboxRemoveSuggestionsFromClipboardDescription[] =
+    "Allow users to remove suggestions from clipboard.";
+
 const char kOmniboxRichEntitySuggestionsName[] =
     "Omnibox rich entity suggestions";
 const char kOmniboxRichEntitySuggestionsDescription[] =