WebViewTestProxyBase: clear out main test delegate upon destruction.

content/shell/test_runner/web_view_test_proxy.cc

Index: content/shell/test_runner/web_view_test_proxy.cc
diff --git a/content/shell/test_runner/web_view_test_proxy.cc b/content/shell/test_runner/web_view_test_proxy.cc
index 140400368a580530b646ff4ab342f4d76ccd43de..3fdc4561976e58938a37b020849e2000f8e7c5e8 100644
--- a/content/shell/test_runner/web_view_test_proxy.cc
+++ b/content/shell/test_runner/web_view_test_proxy.cc
@@ -32,6 +32,8 @@ WebViewTestProxyBase::WebViewTestProxyBase()
 
 WebViewTestProxyBase::~WebViewTestProxyBase() {
   test_interfaces_->WindowClosed(this);
+  if (test_interfaces_->GetDelegate() == delegate_)
+    test_interfaces_->SetDelegate(nullptr);

[tasak, 2017/03/07 03:06:01]

I think, this breaks "--single-process".

Received signal 6
#0 0x7f2824a7939c base::debug::StackTrace::StackTrace()
#1 0x7f2824a78f01 base::debug::(anonymous namespace)::StackDumpSignalHandler()
#2 0x7f28247aa330 <unknown>
#3 0x7f281cdb4c37 gsignal
#4 0x7f281cdb8028 abort
#5 0x7f2824a76c75 base::debug::BreakDebugger()
#6 0x7f2824a966c6 logging::LogMessage::~LogMessage()
#7 0x7f28202c9546 test_runner::GamepadController::Create()
#8 0x7f28202dd39c test_runner::TestInterfaces::SetDelegate()
#9 0x7f282030fe60 test_runner::WebViewTestProxyBase::~WebViewTestProxyBase()
#10 0x000000565b55
_ZN11test_runner16WebViewTestProxyIN7content14RenderViewImplEJPNS1_22CompositorDependenciesERKNS1_5mojom16CreateViewParamsEEED0Ev
#11 0x7f2823d2843d
_ZN4base8internal9BindStateIMN7content12RenderWidgetEFvvEJ13scoped_refptrIS3_EEE7DestroyEPKNS0_13BindStateBaseE
#12 0x7f2824a79eff base::debug::TaskAnnotator::RunTask()


SetDelegate(nullptr) invokes test_runner::GamepadController::Create(nullptr).

 }
 
 void WebViewTestProxyBase::SetInterfaces(WebTestInterfaces* interfaces) {