libstdc++: do not assume std::pair copy constructor is available inserting omnibox pedals

In libstdc++, std::pair copy constructor is deleted. So inserting into a map with a pair
constructed with brace notation will fail, as it will imply a copy. Instead of that,
use make_pair for populating the map of omnibox pedal implementations.

Bug: 957519
Change-Id: I1de69e655c2aa6f8f7cbbd0de86613863aa2dd92
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1584293Reviewed-by: Tommy Li <tommycli@chromium.org>
Commit-Queue: José Dapena Paz <jose.dapena@lge.com>
Cr-Commit-Position: refs/heads/master@{#655964}

components/omnibox/browser/omnibox_pedal_implementations.cc

@@ -142,7 +142,7 @@ std::unordered_map<OmniboxPedalId, std::unique_ptr<OmniboxPedal>>
 GetPedalImplementations() {
   std::unordered_map<OmniboxPedalId, std::unique_ptr<OmniboxPedal>> pedals;
   const auto add = [&](OmniboxPedalId id, OmniboxPedal* pedal) {
-    pedals.insert({id, std::unique_ptr<OmniboxPedal>(pedal)});
+    pedals.insert(std::make_pair(id, std::unique_ptr<OmniboxPedal>(pedal)));
   };
   add(OmniboxPedalId::CLEAR_BROWSING_DATA, new OmniboxPedalClearBrowsingData());
   add(OmniboxPedalId::CHANGE_SEARCH_ENGINE,