AW: avoid std::unique_ptr in favor of make_unique

No change to logic, this just changes explicit calls to the
std::unique_ptr constructor to instead use make_unique() or implicit
conversion from nullptr. This is to conform with a chromium presubmit
check.

Test: ninja -C out/Default android_webview:common
Change-Id: If7ebeb1c67e9b5d07b13728cb3971b45491463ee
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1783702
Auto-Submit: Nate Fischer <ntfschr@chromium.org>
Reviewed-by: Tao Bai <michaelbai@chromium.org>
Commit-Queue: Nate Fischer <ntfschr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#692924}

android_webview/browser/aw_contents.cc

@@ -668,8 +668,8 @@ void AwContents::RequestProtectedMediaIdentifierPermission(
     const GURL& origin,
     base::OnceCallback<void(bool)> callback) {
   permission_request_handler_->SendRequest(
-      std::unique_ptr<AwPermissionRequestDelegate>(new SimplePermissionRequest(
-          origin, AwPermissionRequest::ProtectedMediaId, std::move(callback))));
+      std::make_unique<SimplePermissionRequest>(
+          origin, AwPermissionRequest::ProtectedMediaId, std::move(callback)));
 }
 
 void AwContents::CancelProtectedMediaIdentifierPermissionRequests(
@@ -691,8 +691,8 @@ void AwContents::RequestGeolocationPermission(
     return;
   }
   permission_request_handler_->SendRequest(
-      std::unique_ptr<AwPermissionRequestDelegate>(new SimplePermissionRequest(
-          origin, AwPermissionRequest::Geolocation, std::move(callback))));
+      std::make_unique<SimplePermissionRequest>(
+          origin, AwPermissionRequest::Geolocation, std::move(callback)));
 }
 
 void AwContents::CancelGeolocationPermissionRequests(const GURL& origin) {
@@ -713,8 +713,8 @@ void AwContents::RequestMIDISysexPermission(
     const GURL& origin,
     base::OnceCallback<void(bool)> callback) {
   permission_request_handler_->SendRequest(
-      std::unique_ptr<AwPermissionRequestDelegate>(new SimplePermissionRequest(
-          origin, AwPermissionRequest::MIDISysex, std::move(callback))));
+      std::make_unique<SimplePermissionRequest>(
+          origin, AwPermissionRequest::MIDISysex, std::move(callback)));
 }
 
 void AwContents::CancelMIDISysexPermissionRequests(const GURL& origin) {

android_webview/browser/aw_devtools_server.cc

@@ -49,7 +49,7 @@ class UnixDomainServerSocketFactory : public content::DevToolsSocketFactory {
             base::BindRepeating(&content::CanUserConnectToDevTools),
             true /* use_abstract_namespace */));
     if (socket->BindAndListen(socket_name_, kBackLog) != net::OK)
-      return std::unique_ptr<net::ServerSocket>();
+      return nullptr;
 
     return std::move(socket);
   }
@@ -63,7 +63,7 @@ class UnixDomainServerSocketFactory : public content::DevToolsSocketFactory {
             base::BindRepeating(&content::CanUserConnectToDevTools),
             true /* use_abstract_namespace */));
     if (socket->BindAndListen(*name, kBackLog) != net::OK)
-      return std::unique_ptr<net::ServerSocket>();
+      return nullptr;
 
     return std::move(socket);
   }

android_webview/browser/aw_web_contents_delegate.cc

@@ -278,12 +278,12 @@ void AwWebContentsDelegate::RequestMediaAccessPermission(
     std::move(callback).Run(
         blink::MediaStreamDevices(),
         blink::mojom::MediaStreamRequestResult::FAILED_DUE_TO_SHUTDOWN,
-        std::unique_ptr<content::MediaStreamUI>());
+        nullptr);
     return;
   }
   aw_contents->GetPermissionRequestHandler()->SendRequest(
-      std::unique_ptr<AwPermissionRequestDelegate>(
-          new MediaAccessPermissionRequest(request, std::move(callback))));
+      std::make_unique<MediaAccessPermissionRequest>(request,
+                                                     std::move(callback)));
 }
 
 void AwWebContentsDelegate::EnterFullscreenModeForTab(