Describe infrastructure request/issue:
Today a developer (dominickn) reported an issue with the CL he was working on
https://codereview.chromium.org/2589503002/

In particular the IOS trybot had failed despite all other trybots passing,
and a commit-queue error was shown:

https://codereview.chromium.org/2589503002/#msg25

"Failed to apply patch for
chrome/browser/android/webapk/webapk_update_data_fetcher.cc:
While running git apply --index -p1;
  error: patch failed:
chrome/browser/android/webapk/webapk_update_data_fetcher.cc:108
  error: chrome/browser/android/webapk/webapk_update_data_fetcher.cc: patch does
not apply

Patch:       chrome/browser/android/webapk/webapk_update_data_fetcher.cc
Index: chrome/browser/android/webapk/webapk_update_data_fetcher.cc
diff --git a/chrome/browser/android/webapk/webapk_update_data_fetcher.cc
b/chrome/browser/android/webapk/webapk_update_data_fetcher.cc
index
a5a20efebe050d58bcb9d3074a7fff60b8fd0524..53a944e6afaae8181b5262efa0eb85924cd964e5
100644
--- a/chrome/browser/android/webapk/webapk_update_data_fetcher.cc
+++ b/chrome/browser/android/webapk/webapk_update_data_fetcher.cc
@@ -108,10 +108,10 @@ void WebApkUpdateDataFetcher::FetchInstallableData() {
     return;
 
   InstallableParams params;
-  params.ideal_icon_size_in_dp =
-      ShortcutHelper::GetIdealHomescreenIconSizeInDp();
-  params.minimum_icon_size_in_dp =
-      ShortcutHelper::GetMinimumHomescreenIconSizeInDp();
+  params.ideal_icon_size_in_px =
+      ShortcutHelper::GetIdealHomescreenIconSizeInPx();
+  params.minimum_icon_size_in_px =
+      ShortcutHelper::GetMinimumHomescreenIconSizeInPx();
   params.check_installable = true;
   params.fetch_valid_icon = true;
   InstallableManager::CreateForWebContents(web_contents());
"

The ios trybot was a red herring, an issue related to libyuv (a separate bug should be filled for this) against whoever owns that trybot.


The real issue is that the patch failed to apply when the CQ tried to land it, as the message says.
However the patch applied cleanly on the trybots... why?

The trybots will fall back to a 3-way merge, whereas the CQ will not.
This is likely for good reasons, as a 3-way merge can do the wrong thing.


I think we should make the above CQ error message clearer to explain this different briefly to developers, to make it clear this is a commit queue apply patch failure, and inform them that they need to rebase and resubmit.