Enable spare RenderProcessHost to be preinitialized.

content/browser/renderer_host/render_process_host_unittest.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <stddef.h>
 
 #include <limits>
 #include <memory>
 #include <vector>
 
 #include "base/memory/ptr_util.h"
 #include "build/build_config.h"
 #include "content/common/frame_messages.h"
+#include "content/public/browser/browser_context.h"
 #include "content/public/browser/content_browser_client.h"
 #include "content/public/common/browser_side_navigation_policy.h"
 #include "content/public/common/content_constants.h"
 #include "content/public/test/mock_render_process_host.h"
+#include "content/public/test/test_browser_context.h"
 #include "content/public/test/test_utils.h"
 #include "content/test/test_render_frame_host.h"
 #include "content/test/test_render_view_host.h"
 #include "content/test/test_web_contents.h"
 #include "third_party/WebKit/public/web/WebSandboxFlags.h"
 
 namespace content {
 
 class RenderProcessHostUnitTest : public RenderViewHostImplTestHarness {};
 
@@ skipping 443 matching lines @@
   // REUSE_PENDING_OR_COMMITTED_SITE policy should now return the process of the
   // main RFH, as it was registered with the regular site URL when it committed.
   main_test_rfh()->PrepareForCommit();
   main_test_rfh()->SendNavigate(0, true, kUrl);
   site_instance = SiteInstanceImpl::CreateForURL(browser_context(), kUrl);
   site_instance->set_process_reuse_policy(
       SiteInstanceImpl::ProcessReusePolicy::REUSE_PENDING_OR_COMMITTED_SITE);
   EXPECT_EQ(main_test_rfh()->GetProcess(), site_instance->GetProcess());
 }
 
+class SpareRenderProcessHostUnitTest : public RenderViewHostImplTestHarness {
+ protected:
+  void SetUp() override {
+    SetRenderProcessHostFactory(&rph_factory_);
+    RenderViewHostImplTestHarness::SetUp();
+    SetContents(NULL);  // Start with no renderers.
+    while (!rph_factory_.GetProcesses()->empty()) {
+      rph_factory_.Remove(rph_factory_.GetProcesses()->back().get());
+    }
+  }
+
+  MockRenderProcessHostFactory rph_factory_;
+};
+
+TEST_F(SpareRenderProcessHostUnitTest, TestRendererTaken) {
+  RenderProcessHost::WarmupSpareRenderProcessHost(browser_context());
+  ASSERT_EQ(1U, rph_factory_.GetProcesses()->size());
+  RenderProcessHost* spare_rph = rph_factory_.GetProcesses()->at(0).get();
+
+  const GURL kUrl1("http://foo.com");
+  SetContents(CreateTestWebContents());
+  NavigateAndCommit(kUrl1);
+  EXPECT_EQ(spare_rph, main_test_rfh()->GetProcess());
+  ASSERT_EQ(1U, rph_factory_.GetProcesses()->size());
+}
+
+TEST_F(SpareRenderProcessHostUnitTest, TestRendererNotTaken) {
+  std::unique_ptr<BrowserContext> alternate_context(new TestBrowserContext());
+  RenderProcessHost::WarmupSpareRenderProcessHost(alternate_context.get());
+  ASSERT_EQ(1U, rph_factory_.GetProcesses()->size());
+  RenderProcessHost* spare_rph = rph_factory_.GetProcesses()->at(0).get();
+
+  const GURL kUrl1("http://foo.com");
+  SetContents(CreateTestWebContents());
+  NavigateAndCommit(kUrl1);
+  EXPECT_NE(spare_rph, main_test_rfh()->GetProcess());
+}
+
+// TODO(mattcary): test storage partition shutdown

[Benoit L, 2017/06/15 22:17:11]

Can you also test the case where the process dies?

[mattcary, 2017/06/16 08:18:56]

That seems to be hard to do in the unittests, but I think I've figured out how
to hold the browser tests and will add those to this patch today.

+
 }  // namespace content