Remove the capturePixelsAsynThen() method on testRunner.

Now that devtools has removed its uses of it, we don't need to keep
this as a synonym for updateAllLifecyclePhasesAndCompositeThen().

This can land after devtools rolls into chromium with:
https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/2208540

R=avi@chromium.org

Bug: 952399
Change-Id: I65f7cc4a3356edf7b6b6ee28d50b5c0c8b68b7d5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2222541Reviewed-by: Avi Drissman <avi@chromium.org>
Commit-Queue: danakj <danakj@chromium.org>
Cr-Commit-Position: refs/heads/master@{#773272}

content/shell/renderer/web_test/test_runner.cc

@@ -595,9 +595,6 @@ gin::ObjectTemplateBuilder TestRunnerBindings::GetObjectTemplateBuilder(
       // setTimeout() to run asynchronously.
       .SetMethod("updateAllLifecyclePhasesAndCompositeThen",
                  &TestRunnerBindings::UpdateAllLifecyclePhasesAndCompositeThen)
-      // TODO(danakj): Remove this when devtools is updated to not use it.
-      .SetMethod("capturePixelsAsyncThen",
-                 &TestRunnerBindings::UpdateAllLifecyclePhasesAndCompositeThen)
       .SetMethod("setAnimationRequiresRaster",
                  &TestRunnerBindings::SetAnimationRequiresRaster)
       .SetMethod("logToStderr", &TestRunnerBindings::LogToStderr)