Add migration code for the EnabledPlugins and DisabledPlugins policies.

chrome/test/data/policy/policy_test_cases.json

 {
   "-- Template --": {
     "intro": "Top-level entries map a policy name to its test parameters, described below. The name of the top level entry should be of the form <policy name>[.suffix]. The optional suffix is used for defining multiple test cases for a single policy.",
 
     "os": ["List of operating systems that support this policy. Valid values:", "win", "linux", "mac", "chromeos", "android", "Defaults to empty if not specified."],
     "official_only": "Whether this policy exists in official builds only. Defaults to |false| if not specified.",
     "can_be_recommended": "Whether a recommended value may be set for the policy. Defaults to |false| if not specified.",
     "test_policy": "A policy dictionary that should make the preferences affected by this policy become policy-controlled. Usually just sets the current policy. Defaults to an empty dictionary if not specified.",
     "note": "If the policy affects any preferences, the following array should be specified with one entry per such preference.",
     "pref_mappings": [
@@ skipping 349 matching lines @@
     "test_policy": { "AutoFillEnabled": false },
     "pref_mappings": [
       { "pref": "autofill.enabled",
         "indicator_tests": [
           { "policy": { "AutoFillEnabled": false } }
         ]
       }
     ]
   },
 
-  "DisabledPlugins": {
+  "DisabledPlugins.0": {
+    "note": "This policy is deprecated. This test tests its migration path.",
     "os": ["win", "linux", "mac", "chromeos"],
-    "test_policy": { "DisabledPlugins": ["Flash"] },
+    "test_policy": { "DisabledPlugins": ["*Flash*"] },
     "pref_mappings": [
-      { "pref": "plugins.plugins_disabled" }
+      { "pref": "profile.managed_default_content_settings.plugins",
+        "indicator_selector": "[content-setting=plugins]",
+        "indicator_tests": [
+          { "policy": { "DisabledPlugins": ["*Flash*"] },
+            "value": "block"}
+        ]
+      }
     ]
   },
 
-  "EnabledPlugins": {
+  "DisabledPlugins.1": {
+    "note": "This policy is deprecated. This test tests its migration path.",
     "os": ["win", "linux", "mac", "chromeos"],
-    "test_policy": { "EnabledPlugins": ["Flash"] },
+    "test_policy": { "DisabledPlugins": ["*PDF*"] },
     "pref_mappings": [
-      { "pref": "plugins.plugins_enabled" }
+      { "pref": "plugins.always_open_pdf_externally",
+        "indicator_tests": [
+          { "policy": { "DisabledPlugins": ["*PDF*"] }}
+        ]
+      }
+    ]
+  },
+
+  "EnabledPlugins.0": {
+    "note": "This policy is deprecated. This test tests its migration path.",
+    "os": ["win", "linux", "mac", "chromeos"],
+    "test_policy": { "EnabledPlugins": ["*Flash*"] },
+    "pref_mappings": [
+      { "pref": "profile.managed_default_content_settings.plugins",
+        "indicator_selector": "[content-setting=plugins]",
+        "indicator_tests": [
+          { "policy": { "EnabledPlugins": ["*Flash*"] },
+            "value": "allow"}
+        ]
+      }
+    ]
+  },
+
+  "EnabledPlugins.1": {
+    "note": "This policy is deprecated. This test tests its migration path.",
+    "os": ["win", "linux", "mac", "chromeos"],
+    "test_policy": { "EnabledPlugins": ["*PDF*"] },
+    "pref_mappings": [
+      { "pref": "plugins.always_open_pdf_externally",
+        "indicator_tests": [
+          { "policy": { "EnabledPlugins": ["*PDF*"] }}
+        ]
+      }
     ]
   },
 
   "DisabledPluginsExceptions": {
-    "os": ["win", "linux", "mac", "chromeos"],
-    "test_policy": { "DisabledPluginsExceptions": ["Flash"] },
-    "pref_mappings": [
-      { "pref": "plugins.plugins_disabled_exceptions" }
-    ]
+    "note": "This policy is deprecated it doesn't map to a pref value anymore.",
+    "os": ["win", "linux", "mac", "chromeos"]
   },
 
   "AlwaysOpenPdfExternally": {
     "os": ["win", "linux", "mac"],
     "test_policy": { "AlwaysOpenPdfExternally": true },
     "pref_mappings": [
       { "pref": "plugins.always_open_pdf_externally",
         "indicator_tests": [
           { "policy": { "AlwaysOpenPdfExternally": false }},
           { "policy": { "AlwaysOpenPdfExternally": true }}
@@ skipping 2513 matching lines @@
 
   "AdditionalLaunchParameters": {
   },
 
   "SuppressChromeFrameTurndownPrompt": {
   },
 
   "SkipMetadataCheck": {
   }
 }