Add BootParameters tests.

Bug: 78577334
Test: Builds on master (aosp_x86-userdebug),
unit tests pass on oc-mr1 (on iot target).

Change-Id: I3584a285f1be914cc3e940469d7dea142d4a4231
diff --git a/cmds/bootanimation/iot/BootParameters.cpp b/cmds/bootanimation/iot/BootParameters.cpp
index da6ad0d..06cdbf8 100644
--- a/cmds/bootanimation/iot/BootParameters.cpp
+++ b/cmds/bootanimation/iot/BootParameters.cpp
@@ -20,8 +20,6 @@
 
 #include <fcntl.h>
 
-#include <string>
-
 #include <android-base/file.h>
 #include <base/json/json_parser.h>
 #include <base/json/json_reader.h>
@@ -98,7 +96,11 @@
         return;
     }
 
-    std::unique_ptr<Value> json = JSONReader::Read(contents);
+    loadParameters(contents);
+}
+
+void BootParameters::loadParameters(const std::string& raw_json) {
+    std::unique_ptr<Value> json = JSONReader::Read(raw_json);
     if (json.get() == nullptr) {
         return;
     }