[chromedriver] Fix print unittest type

PrintParams should be of type base::DictionaryValue

Bug: chromedriver:3481
Change-Id: I4dae87d6e1a88585d592a1be85b757ff01d8d869
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2324668
Auto-Submit: Shengfa Lin <shengfa@google.com>
Commit-Queue: John Chen <johnchen@chromium.org>
Reviewed-by: John Chen <johnchen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#792465}

chrome/test/chromedriver/window_commands_unittest.cc

@@ -414,7 +414,7 @@ TEST(WindowCommandsTest, ExecutePrintDefaultParams) {
   Status status =
       CallWindowCommand(ExecutePrint, &webview, params, &result_value);
   ASSERT_EQ(kOk, status.code()) << status.message();
-  base::Value printParams = getDefaultPrintParams();
+  base::DictionaryValue printParams = getDefaultPrintParams();
   ASSERT_EQ(static_cast<const base::Value&>(printParams), webview.getParams());
 }