Roll googletest to 1.8.0.

build/secondary/testing/gtest/BUILD.gn

Index: build/secondary/testing/gtest/BUILD.gn
diff --git a/build/secondary/testing/gtest/BUILD.gn b/build/secondary/testing/gtest/BUILD.gn
index 649f5c559db4054f6815b77432f39e04e0ca769e..637048cc42d9eae688b1e5d6331d08b65d54f4fa 100644
--- a/build/secondary/testing/gtest/BUILD.gn
+++ b/build/secondary/testing/gtest/BUILD.gn
@@ -2,6 +2,13 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+# Chromium's GN configuration for gtest now lives at testing/gtest/BUILD.gn.
+#
+# This configuration is left in the tree because it is pulled by V8 and PDFium,
+# and will be removed as soon as the projects switch off of it.

[Nico, 2017/04/28 20:56:23]

I think we should either just remove this or make it forward to the new
locations. v8 and pdfium can then merge this change the next time they pull
chromium. Having this here might confuse gn and it won't pick up the new
BUILD.gn.

[pwnall, 2017/04/29 00:16:26]

If we remove build/secondary, v8 and pdifum can't merge Chromium until they land
a variation of this Google Test migration CL. I was afraid that hard consistency
would be a lot more difficult to achieve than eventual consistency.

FWIW, according to the bots and local results, GN seems to use build/secondary
as a fallback. So, while humans and other tools might get confused, GN doesn't
seem to.

I don't really know how often V8 or PDFium update build/, so I don't know if
this is an actual problem. Do you still think we should remove build/secondary
in this CL?

[Nico, 2017/05/01 17:52:54]

Ok, let's do this separately.

This kind of raises the question: How are pdfium etc use this at all? They'll
need third_party/googletest/BUILD.gn, so I suppose we'll have to ask infra to
mirror out third_party/googletest to https://chromium.googlesource.com/ and then
those projects will have to deps in both that repo and the actual gtest repo?

+#
+# Details at http://crbug.com/630705 and http://crrev.com/2779193002
+
 import("//build_overrides/gtest.gni")
 
 config("gtest_config") {