Add WP test for CSPEE with the plugin-types directive

Bug: 1094909
Change-Id: Ia823b00ae5f62188547f714026d7dece11b9933e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2351771
Commit-Queue: Antonio Sartori <antoniosartori@chromium.org>
Reviewed-by: Arthur Sonzogni <arthursonzogni@chromium.org>
Reviewed-by: Mike West <mkwst@chromium.org>
Cr-Commit-Position: refs/heads/master@{#804872}

third_party/blink/web_tests/external/wpt/content-security-policy/embedded-enforcement/subsumption_algorithm-general.html

@@ -60,6 +60,14 @@
         "returned_csp": "style-src http://*.example.com:*",
         "returned_csp_2": "style-src http://*.com",
         "expected": IframeLoad.EXPECT_LOAD },
+      { "name": "Iframe should block if plugin-types directive is not subsumed.",
+        "required_csp": "plugin-types application/pdf",
+        "returned_csp": null,
+        "expected": IframeLoad.EXPECT_BLOCK },
+      { "name": "Iframe should load if plugin-types directive is subsumed.",
+        "required_csp": "plugin-types application/pdf application/x-java-applet",
+        "returned_csp": "plugin-types application/pdf",
+        "expected": IframeLoad.EXPECT_LOAD },
     ];
 
     tests.forEach(test => {