Always remove errored Resource from MemoryCache

Previously, preloaded Resources are not evicted from MemoryCache
in some cases, even when it is errored, in order to prevent
duplicated requests to an errored URL (once as a preloading request and
once as a non-preloading request). But now this exception is not
needed because Issue 652228 made preload matching done outside
MemoryCache.

This CL removes that exception and makes errored Resources always
evicted from MemoryCache.

Bug: 652228
Change-Id: I706b733574f9a753cb8d001a2be53f78b0d9933c
Reviewed-on: https://chromium-review.googlesource.com/721845
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Reviewed-by: Yutaka Hirano <yhirano@chromium.org>
Commit-Queue: Hiroshige Hayashizaki <hiroshige@chromium.org>
Cr-Commit-Position: refs/heads/master@{#509506}

third_party/WebKit/Source/platform/loader/fetch/Resource.cpp

@@ -422,7 +422,7 @@ void Resource::FinishAsError(const ResourceError& error,
   error_ = error;
   is_revalidating_ = false;
 
-  if ((error_.IsCancellation() || !is_unused_preload_) && IsMainThread())
+  if (IsMainThread())
     GetMemoryCache()->Remove(this);
 
   if (!ErrorOccurred())