Sync more GN unit tests with GYP.

components/search/BUILD.gn

Index: components/search/BUILD.gn
diff --git a/components/search/BUILD.gn b/components/search/BUILD.gn
index 21c49c4dcc4f1882a238f1dc7a4f4f59709593b2..8e18d8c6bd77145c01f39e3cb848b1b49540e36d 100644
--- a/components/search/BUILD.gn
+++ b/components/search/BUILD.gn
@@ -2,7 +2,7 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-static_library("search") {
+source_set("search") {
   sources = [
     "search.cc",
     "search.h",
@@ -17,3 +17,15 @@ static_library("search") {
     "//url",
   ]
 }
+
+source_set("unit_tests") {
+  testonly = true
+  sources = [
+    "search_android_unittest.cc",
+    "search_unittest.cc",
+  ]
+  deps = [
+    ":search",
+    "//testing/gtest",
+  ]
+}