Add about:flags support for doc.write script blocking.

third_party/WebKit/LayoutTests/http/tests/loading/doc-write-sync-third-party-script-conn-type.html

Index: third_party/WebKit/LayoutTests/http/tests/loading/doc-write-sync-third-party-script-conn-type.html
diff --git a/third_party/WebKit/LayoutTests/http/tests/loading/doc-write-sync-third-party-script-conn-type.html b/third_party/WebKit/LayoutTests/http/tests/loading/doc-write-sync-third-party-script-conn-type.html
index 99854a8d8ca5a0b54c12469b6e7e813d523a2b74..913f4af0b8218f231e5b9bae78a8bb591b41851c 100644
--- a/third_party/WebKit/LayoutTests/http/tests/loading/doc-write-sync-third-party-script-conn-type.html
+++ b/third_party/WebKit/LayoutTests/http/tests/loading/doc-write-sync-third-party-script-conn-type.html
@@ -6,14 +6,14 @@
     var jsLoaded = false;
     var loadSuccess = false;
     if (window.internals) {
-        internals.settings.setDisallowFetchForDocWrittenScriptsInMainFrame(true);
+        internals.settings.setDisallowFetchForDocWrittenScriptsInMainFrameOnSlowConnections(true);
         internals.setNetworkStateNotifierTestOnly(true);
         internals.setNetworkConnectionInfo('cellular3g', 2.0);
         internals.evictAllResources();
 
         window.addEventListener('beforeunload', function() {
             internals.setNetworkStateNotifierTestOnly(false);
-            internals.settings.setDisallowFetchForDocWrittenScriptsInMainFrame(false);
+            internals.settings.setDisallowFetchForDocWrittenScriptsInMainFrameOnSlowConnections(false);
         }, false);
     }

[shivanisha, 2016/04/11 14:26:56]

May be add another test case in this file which sets the flag independent of
connection type to be true and then blocking should happen for a script in
'cellular3g' as well.

[Bryan McQuade, 2016/04/11 16:28:30]

Sure. I decided to add a new test file for this one since I felt it was a little
hairy to be changing internals settings multiple times through a single test
file. Hope that is ok. Let me know what you think.

[shivanisha, 2016/04/11 16:57:56]

I am good either ways. 
Since the test is synchronous, changing internal settings between two tests in
the same file should be fine, though.

[Bryan McQuade, 2016/04/11 18:15:40]

I think I like this slightly better since it's easier to reason about test set
up and tear down as happening once at beginning and end of the test life cycle.
I can switch it if you prefer. Let me know. Thanks!

[shivanisha, 2016/04/11 19:01:07]

Sounds good to me to have separate test files. Thanks!

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