Remove EventSender from ImageLoader

third_party/WebKit/LayoutTests/http/tests/resources/srcset-helper.js

Index: third_party/WebKit/LayoutTests/http/tests/resources/srcset-helper.js
diff --git a/third_party/WebKit/LayoutTests/http/tests/resources/srcset-helper.js b/third_party/WebKit/LayoutTests/http/tests/resources/srcset-helper.js
index 90b869a404b3f219a2b3e349f5f8476888a1555e..3e5bc9fb9ee86362540a099f60164cdba59249dc 100644
--- a/third_party/WebKit/LayoutTests/http/tests/resources/srcset-helper.js
+++ b/third_party/WebKit/LayoutTests/http/tests/resources/srcset-helper.js
@@ -21,11 +21,17 @@ function runTest() {
     } else {
         // Right now there is a bug that srcset does not properly deal with dynamic changes to the scale factor,
         // so to work around that, we must reload the page to get the new image.
-        sessionStorage.pageReloaded = true;
-        if (window.internals) {
-            internals.evictAllResources();
-        }
-        document.location.reload(true);
+        //
+        // At the time of the Document load event, there might be other
+        // ongoing tasks that can cause new images to be loaded. To evict
+        // those images, we delay evictAllResources() call a little.
+        setTimeout(function() {
+          sessionStorage.pageReloaded = true;
+          if (window.internals) {
+              internals.evictAllResources();
+          }
+          document.location.reload(true);
+        }, 300);

[kinuko, 2017/05/08 09:24:24]

This intuitively feels a bit sketchy, is 300 chosen arbitrarily? Would it be
hard to make this deterministic?

[kouhei (in TOK), 2017/05/08 11:54:25]

Tip: use requestAnimationFrame?

[hiroshige, 2017/05/08 19:23:10]

I think we can make this deterministic by using iframes, i.e. set scale factor
in the main HTML and then after that start loading the iframe that contains the
tests.

However, this requires changes to 9 test HTMLs under http/tests/loading that use
srcset-helper.js.
Also, about 40 tests are using srcset-helper.js under fast/.
(They are not affected by this CL because they are not interested in preloading
though)

Therefore I chose to add workaround here not to block this CL by the test
refactoring.
requestAnimationFrame didn't work :(
setTimeout(, 0) works.

     }
 }