Unit test FindInPageMediator.

ios/clean/chrome/browser/ui/find_in_page/BUILD.gn

Index: ios/clean/chrome/browser/ui/find_in_page/BUILD.gn
diff --git a/ios/clean/chrome/browser/ui/find_in_page/BUILD.gn b/ios/clean/chrome/browser/ui/find_in_page/BUILD.gn
index 1274e30a27f48e1b55e0993c2240a0b14394796e..a53b364004e1b3a514da48b3e46610b0bafb513d 100644
--- a/ios/clean/chrome/browser/ui/find_in_page/BUILD.gn
+++ b/ios/clean/chrome/browser/ui/find_in_page/BUILD.gn
@@ -48,3 +48,20 @@ source_set("find_in_page_ui") {
   libs = [ "UIKit.framework" ]
   configs += [ "//build/config/compiler:enable_arc" ]
 }
+
+source_set("unit_tests") {
+  sources = [
+    "find_in_page_mediator_unittest.mm",
+  ]
+  deps = [
+    ":find_in_page",
+    ":find_in_page_ui",
+    "//base",
+    "//ios/chrome/browser/web_state_list",
+    "//ios/chrome/browser/web_state_list:test_support",
+    "//testing/gtest",
+    "//third_party/ocmock",
+  ]
+  configs += [ "//build/config/compiler:enable_arc" ]
+  testonly = true
+}