Nothing obvious in blame set.

Suspecting https://codereview.chromium.org/2653303002/

Reverting here: https://codereview.chromium.org/2657603005/

dpranke, pointed out that in the subsequent build (#51254, did not contain the revert), the file compiled just fine:

https://build.chromium.org/p/chromium/builders/Win/builds/51254

obj/content/app/content_main_runner_child/content_main_runner.obj

There's a missing dependency, looks like.

content_main_runner is part of //content/app:content_main_runner_both

gpu_host.mojom.h is generated by //services/ui/gpu/interfaces:interfaces__generator . That file is a dependency of //content/gpu:gpu_sources, which is a dependency of //content/app:content_main_runner_both everywhere *except* in the release win builds (where is_multi_dll_chrome is true).

I don't know if that logic was originally correct and has changed, or if it was always wrong.

Assigning to brettw@, who wrote it.

I think https://codereview.chromium.org/2661563002 is a reasonable fix for this.

Ahh I didn't know there was a bug for this, I was pinged by the sheriff today and looked into this, I found:

commit 72aae8ab52b19f803d4a1ef794bb5783190bf32b
Author: sadrul <sadrul@chromium.org>
Date:   Mon Jan 23 20:52:32 2017 -0800

    gpu: Use mus gpu interface in non-mus chrome.
    [...]

which changed

+++ b/content/browser/gpu/gpu_process_host.h
@@ -28,7 +28,10 @@
[...]
+#include "services/ui/gpu/interfaces/gpu_host.mojom.h"
 #include "services/ui/gpu/interfaces/gpu_main.mojom.h"
+#include "services/ui/gpu/interfaces/gpu_service.mojom.h"
[...]


/content/browser/gpu/gpu_process_host.h is included by 
./content/app/content_main_runner.cc

I pinged sadrul@ who owns that commit.

content/browser's dependency on //services/ui/gpu/interfaces needs to move from deps to public_deps

I considered that, but I don't think that will fix the problem (see comments 3 and 4 above)? From what I can see, content/app:content_main_runner_child does not seem to actually have a dependency on content/browser, so adding gpu/interfaces to content/browser's public_deps probably won't help?

The annoying thing is that every time this happens, it results in a tree closure. It caused three tree closures today only: https://chromium-status.appspot.com/

Three tree closures in one day from this is definitely unusual.

But, yes, missing dependencies are bad and we should fix this ASAP.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/e0d5a0de9a938f88ae2f9fe35b5186b352ca6021

commit e0d5a0de9a938f88ae2f9fe35b5186b352ca6021
Author: sadrul <sadrul@chromium.org>
Date: Mon Jan 30 19:09:02 2017

win: Fix flaky compile failures.

content_main_runner.cc has a dependency on gpu_process_host.h, which has
a dependency on a mojom-generated header file. But this dependency is
required only in a non-multi-dll build. So add the proper #ifdef's to
make sure the problematic dependencies are avoided in multi-dll build.

BUG= 685440 

Review-Url: https://codereview.chromium.org/2661563002
Cr-Commit-Position: refs/heads/master@{#447027}

[modify] https://crrev.com/e0d5a0de9a938f88ae2f9fe35b5186b352ca6021/content/app/content_main_runner.cc