Split content script injections into multiple tasks

chrome/test/data/extensions/api_test/content_scripts/about_blank_iframes/test.js

Index: chrome/test/data/extensions/api_test/content_scripts/about_blank_iframes/test.js
diff --git a/chrome/test/data/extensions/api_test/content_scripts/about_blank_iframes/test.js b/chrome/test/data/extensions/api_test/content_scripts/about_blank_iframes/test.js
index 5d08ce0a68dd5d10f773dea4f73eff7770fbdd86..099b0b538d48e0c55a46310b3bbb0663ecda9790 100644
--- a/chrome/test/data/extensions/api_test/content_scripts/about_blank_iframes/test.js
+++ b/chrome/test/data/extensions/api_test/content_scripts/about_blank_iframes/test.js
@@ -43,19 +43,12 @@ chrome.test.getConfig(function(config) {
       chrome.tabs.create({ url: test_url });
     },
     function testDocumentStartRunsInSameWorldAsDocumentEndOfJavaScriptUrl() {
-      var hasReceivedFirstMessage = false;
       onRequest.addListener(function listener(request) {
-        if (!hasReceivedFirstMessage) {
-          hasReceivedFirstMessage = true;
-          // Step one: Empty document where the JavaScript code was executed.
-          checkFirstMessageEquals('jsresult/')(request);
-        } else {
-          onRequest.removeListener(listener);
-          // Step 2: The empty document was replaced with the result of
-          // the evaluated JavaScript code.
-          checkFirstMessageEquals('jsresult/something')(request);
-          chrome.test.succeed();
-        }
+        onRequest.removeListener(listener);

[Devlin, 2017/03/02 02:33:17]

why this change?

[Kunihiko Sakamoto, 2017/03/06 09:11:05]

It has been answered here :)
https://codereview.chromium.org/2633253002/diff/200001/chrome/test/data/exten...

[Devlin, 2017/03/10 03:18:44]

Whoops!  Sorry for the dupe. :)

This still makes me a little worried, though - I thought the intention was that
this CL should only have an impact when the associated switch is included.  Why
is this delaying document_end scripts in all cases?

[Kunihiko Sakamoto, 2017/03/10 07:07:28]

The behavior does not change unless the flag is enabled, but since
ContentScriptApiTest is now parameterized, I changed this test to be more
permissive, to pass in both cases.

In Patch Set 9, I've reverted that and made the test aware of the flag,
expecting current behavior when the flag is disabled.

[Devlin, 2017/03/14 15:08:55]

Thanks; Patch Set 9 makes a lot more sense to me.  Otherwise, I'd expect this to
fail without the switch, since the first message would still be 'jsresult/'
(and, patching in the CL, it seems it did).

+        // The empty document was replaced with the result of the evaluated
+        // JavaScript code.
+        checkFirstMessageEquals('jsresult/something')(request);
+        chrome.test.succeed();
       });
       chrome.test.log('Creating tab...');
       var test_url =