Extension API: Rename contentSettings.misc to .global and rename preferences under it.

chrome/test/data/extensions/api_test/content_settings/clear/test.html

 <script>
 // Content settings API test
 // Run with browser_tests --gtest_filter=ExtensionApiTest.ContentSettingsClear
 
 var cs = chrome.experimental.contentSettings;
 chrome.test.runTests([
-  function getBlockThirdPartyCookies() {
-    cs.misc.blockThirdPartyCookies.get({}, chrome.test.callbackPass(
-        function(block) {
+  function getThirdPartyCookiesAllowed() {
+    cs.global.thirdPartyCookiesAllowed.get({}, chrome.test.callbackPass(
+        function(allowed) {
           chrome.test.assertEq(
-              block,
+              allowed,
               {
-                'value': true,
+                'value': false,
                 'levelOfControl': "controllable_by_this_extension"
               },
               "third-party cookies should be blocked");
         }));
   },
-  function setBlockThirdPartyCookies() {
-    cs.misc.blockThirdPartyCookies.set(
-        {'value': false},
+  function setThirdPartyCookiesAllowed() {
+    cs.global.thirdPartyCookiesAllowed.set(
+        {'value': true},
         chrome.test.callbackPass());
   },
-  function clearBlockThirdPartyCookies() {
-    cs.misc.blockThirdPartyCookies.clear({}, chrome.test.callbackPass());
+  function clearThirdPartyCookiesAllowed() {
+    cs.global.thirdPartyCookiesAllowed.clear({}, chrome.test.callbackPass());
   },
-  function getBlockThirdPartyCookies2() {
-    cs.misc.blockThirdPartyCookies.get({}, chrome.test.callbackPass(
-        function(block) {
+  function getThirdPartyCookiesAllowed2() {
+    cs.global.thirdPartyCookiesAllowed.get({}, chrome.test.callbackPass(
+        function(allowed) {
           chrome.test.assertEq(
-              block,
+              allowed,
               {
-                'value': true,
+                'value': false,
                 'levelOfControl': "controllable_by_this_extension"
               },
               "third-party cookies should be blocked");
         }));
   }
 ]);
 </script>