Add some tests for ThrottlingResourceHandler.

content/browser/loader/throttling_resource_handler_unittest.cc

Index: content/browser/loader/throttling_resource_handler_unittest.cc
diff --git a/content/browser/loader/throttling_resource_handler_unittest.cc b/content/browser/loader/throttling_resource_handler_unittest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..cc8525ba4a6a5871dc88eeaf8ade2f059e7fa6a1
--- /dev/null
+++ b/content/browser/loader/throttling_resource_handler_unittest.cc
@@ -0,0 +1,857 @@
+// Copyright 2016 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 "content/browser/loader/throttling_resource_handler.h"
+
+#include <memory>
+
+#include "base/macros.h"
+#include "base/memory/ptr_util.h"
+#include "base/memory/scoped_vector.h"
+#include "base/message_loop/message_loop.h"
+#include "content/browser/loader/mock_resource_loader.h"
+#include "content/browser/loader/resource_request_info_impl.h"
+#include "content/browser/loader/test_resource_handler.h"
+#include "content/public/browser/resource_throttle.h"
+#include "content/public/common/resource_response.h"
+#include "net/base/request_priority.h"
+#include "net/url_request/redirect_info.h"
+#include "net/url_request/url_request.h"
+#include "net/url_request/url_request_test_util.h"
+#include "testing/gtest/include/gtest/gtest.h"
+#include "url/gurl.h"
+
+namespace content {
+namespace {
+
+const char kInitialUrl[] = "http://initial/";
+const char kRedirectUrl[] = "http://redirect/";
+
+class TestResourceThrottle : public ResourceThrottle {
+ public:
+  explicit TestResourceThrottle(TestResourceThrottle* previous_throttle) {
+    if (previous_throttle) {
+      DCHECK(!previous_throttle->next_throttle_);
+      previous_throttle_ = previous_throttle;
+      previous_throttle_->next_throttle_ = this;
+    }
+  }
+
+  ~TestResourceThrottle() override {}
+
+  // Sets the throttle after this one, to enable checks that they're called in
+  // the expected order.
+  void SetNextThrottle(TestResourceThrottle* throttle) {
+    DCHECK(!next_throttle_);
+    DCHECK(!throttle->previous_throttle_);
+
+    next_throttle_ = throttle;
+    throttle->previous_throttle_ = this;
+  }
+
+  // ResourceThrottle implemenation:
+
+  void WillStartRequest(bool* defer) override {
+    EXPECT_EQ(0, will_start_request_called_);
+    EXPECT_EQ(0, will_redirect_request_called_);
+    EXPECT_EQ(0, will_process_response_called_);
+
+    if (previous_throttle_) {
+      EXPECT_EQ(1, previous_throttle_->will_start_request_called_);
+      EXPECT_EQ(0, previous_throttle_->will_redirect_request_called_);
+      EXPECT_EQ(0, previous_throttle_->will_process_response_called_);
+    }
+
+    if (next_throttle_) {
+      EXPECT_EQ(0, next_throttle_->will_start_request_called_);
+      EXPECT_EQ(0, next_throttle_->will_redirect_request_called_);
+      EXPECT_EQ(0, next_throttle_->will_process_response_called_);
+    }
+
+    ++will_start_request_called_;
+    *defer = defer_on_will_start_request_;
+    if (cancel_on_will_start_request_)
+      CancelWithError(net::ERR_UNEXPECTED);
+  }
+
+  void WillRedirectRequest(const net::RedirectInfo& redirect_info,
+                           bool* defer) override {
+    EXPECT_EQ(GURL(kRedirectUrl), redirect_info.new_url);
+
+    EXPECT_EQ(1, will_start_request_called_);
+    // None of these tests use multiple redirects.
+    EXPECT_EQ(0, will_redirect_request_called_);
+    EXPECT_EQ(0, will_process_response_called_);
+
+    if (previous_throttle_) {
+      EXPECT_EQ(1, previous_throttle_->will_start_request_called_);
+      EXPECT_EQ(1, previous_throttle_->will_redirect_request_called_);
+      EXPECT_EQ(0, previous_throttle_->will_process_response_called_);
+    }
+
+    if (next_throttle_) {
+      EXPECT_EQ(1, next_throttle_->will_start_request_called_);
+      EXPECT_EQ(0, next_throttle_->will_redirect_request_called_);
+      EXPECT_EQ(0, next_throttle_->will_process_response_called_);
+    }
+
+    ++will_redirect_request_called_;
+    *defer = defer_on_will_redirect_request_;
+    if (cancel_on_will_redirect_request_)
+      CancelWithError(net::ERR_UNEXPECTED);
+  }
+
+  void WillProcessResponse(bool* defer) override {
+    EXPECT_EQ(0, will_process_response_called_);
+
+    if (previous_throttle_)
+      EXPECT_EQ(1, previous_throttle_->will_process_response_called_);
+
+    if (next_throttle_)
+      EXPECT_EQ(0, next_throttle_->will_process_response_called_);
+
+    ++will_process_response_called_;
+    *defer = defer_on_will_process_response_;
+    if (cancel_on_will_process_response_)
+      CancelWithError(net::ERR_UNEXPECTED);
+  }
+
+  const char* GetNameForLogging() const override { return "Hank"; }
+
+  int will_start_request_called() const { return will_start_request_called_; }
+  int will_redirect_request_called() const {
+    return will_redirect_request_called_;
+  }
+  int will_process_response_called() const {
+    return will_process_response_called_;
+  }
+
+  void set_defer_on_will_start_request(bool defer_on_will_start_request) {
+    defer_on_will_start_request_ = defer_on_will_start_request;
+  }
+  void set_defer_on_will_redirect_request(bool defer_on_will_redirect_request) {
+    defer_on_will_redirect_request_ = defer_on_will_redirect_request;
+  }
+  void set_defer_on_will_process_response(bool defer_on_will_process_response) {
+    defer_on_will_process_response_ = defer_on_will_process_response;
+  }
+
+  void set_cancel_on_will_start_request(bool cancel_on_will_start_request) {
+    cancel_on_will_start_request_ = cancel_on_will_start_request;
+  }
+  void set_cancel_on_will_redirect_request(
+      bool cancel_on_will_redirect_request) {
+    cancel_on_will_redirect_request_ = cancel_on_will_redirect_request;
+  }
+  void set_cancel_on_will_process_response(
+      bool cancel_on_will_process_response) {
+    cancel_on_will_process_response_ = cancel_on_will_process_response;
+  }
+
+  using ResourceThrottle::Resume;
+  using ResourceThrottle::CancelWithError;
+
+ private:
+  int will_start_request_called_ = 0;
+  int will_redirect_request_called_ = 0;
+  int will_process_response_called_ = 0;
+
+  bool defer_on_will_start_request_ = false;
+  bool defer_on_will_redirect_request_ = false;
+  bool defer_on_will_process_response_ = false;
+
+  bool cancel_on_will_start_request_ = false;
+  bool cancel_on_will_redirect_request_ = false;
+  bool cancel_on_will_process_response_ = false;
+
+  TestResourceThrottle* previous_throttle_ = nullptr;
+  TestResourceThrottle* next_throttle_ = nullptr;
+
+  DISALLOW_COPY_AND_ASSIGN(TestResourceThrottle);
+};
+
+class ThrottlingResourceHandlerTest : public testing::Test {
+ public:
+  ThrottlingResourceHandlerTest()
+      : never_started_url_request_(request_context_.CreateRequest(
+            GURL(kInitialUrl),
+            net::DEFAULT_PRIORITY,
+            &never_started_url_request_delegate_)),
+        throttle1_(new TestResourceThrottle(nullptr)),
+        throttle2_(new TestResourceThrottle(throttle1_)),
+        test_handler_(new TestResourceHandler()) {
+    ScopedVector<ResourceThrottle> throttles;
+    throttles.push_back(base::WrapUnique(throttle1_));
+    throttles.push_back(base::WrapUnique(throttle2_));
+    throttling_handler_.reset(new ThrottlingResourceHandler(
+        base::WrapUnique(test_handler_), never_started_url_request_.get(),
+        std::move(throttles)));
+    mock_loader_.reset(new MockResourceLoader(throttling_handler_.get()));
+
+    // Basic initial state sanity checks.
+    EXPECT_EQ(0, test_handler_->on_will_start_called());
+    EXPECT_EQ(0, throttle1_->will_start_request_called());
+    EXPECT_EQ(0, throttle2_->will_start_request_called());
+  }
+
+  // Finish the request with a 0-byte read and success.  All of this is just
+  // passed through to the TestResourceHandler, so is uninterested for these

[Randy Smith (Not in Mondays), 2016/12/20 22:16:41]

nit: "is uninterested" ?

[mmenke, 2017/01/04 22:02:29]

Done.

+  // tests.
+  void FinishRequestSuccessfully() {
+    EXPECT_EQ(0, test_handler_->on_will_read_called());
+
+    ASSERT_EQ(MockResourceLoader::Status::IDLE, mock_loader_->OnWillRead(1));
+    EXPECT_EQ(1, test_handler_->on_will_read_called());
+    EXPECT_EQ(0, test_handler_->on_read_completed_called());
+
+    ASSERT_EQ(MockResourceLoader::Status::IDLE,
+              mock_loader_->OnReadCompleted(0));
+    EXPECT_EQ(1, test_handler_->on_read_completed_called());
+    EXPECT_EQ(0, test_handler_->on_response_completed_called());
+
+    ASSERT_EQ(MockResourceLoader::Status::IDLE,
+              mock_loader_->OnResponseCompleted(
+                  net::URLRequestStatus::FromError(net::OK)));
+    EXPECT_EQ(net::OK, mock_loader_->error_code());
+    EXPECT_EQ(1, test_handler_->on_read_completed_called());
+    EXPECT_EQ(1, test_handler_->on_response_completed_called());
+  }
+
+ protected:
+  // Needs to be first, so it's destroyed last.
+  base::MessageLoopForIO message_loop_;
+
+  // Machinery to construct a URLRequest that's just used as an argument to
+  // methods that expect one, and is never actually started.
+  net::TestURLRequestContext request_context_;
+  net::TestDelegate never_started_url_request_delegate_;
+  std::unique_ptr<net::URLRequest> never_started_url_request_;
+
+  // Owned by test_handler_;
+  TestResourceThrottle* throttle1_;
+  TestResourceThrottle* throttle2_;
+
+  // Owned by |throttling_handler_|.
+  TestResourceHandler* test_handler_;
+  std::unique_ptr<ThrottlingResourceHandler> throttling_handler_;
+  std::unique_ptr<MockResourceLoader> mock_loader_;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(ThrottlingResourceHandlerTest);
+};
+
+TEST_F(ThrottlingResourceHandlerTest, Sync) {
+  ASSERT_EQ(MockResourceLoader::Status::IDLE,
+            mock_loader_->OnWillStart(GURL(kInitialUrl)));
+  EXPECT_EQ(1, throttle1_->will_start_request_called());
+  EXPECT_EQ(0, throttle1_->will_redirect_request_called());
+
+  EXPECT_EQ(1, throttle2_->will_start_request_called());
+
+  EXPECT_EQ(1, test_handler_->on_will_start_called());
+  EXPECT_EQ(0, test_handler_->on_request_redirected_called());
+
+  net::RedirectInfo redirect_info;
+  redirect_info.status_code = 301;
+  redirect_info.new_url = GURL(kRedirectUrl);
+  ASSERT_EQ(
+      MockResourceLoader::Status::IDLE,
+      mock_loader_->OnRequestRedirected(redirect_info, new ResourceResponse()));
+  EXPECT_EQ(1, throttle1_->will_redirect_request_called());
+  EXPECT_EQ(0, throttle1_->will_process_response_called());
+
+  EXPECT_EQ(1, throttle2_->will_redirect_request_called());
+
+  EXPECT_EQ(1, test_handler_->on_request_redirected_called());
+  EXPECT_EQ(0, test_handler_->on_response_started_called());
+
+  ASSERT_EQ(MockResourceLoader::Status::IDLE,
+            mock_loader_->OnResponseStarted(new ResourceResponse()));
+  EXPECT_EQ(1, throttle1_->will_process_response_called());
+  EXPECT_EQ(1, throttle2_->will_process_response_called());
+
+  EXPECT_EQ(1, test_handler_->on_request_redirected_called());
+  EXPECT_EQ(1, test_handler_->on_response_started_called());
+  EXPECT_EQ(0, test_handler_->on_read_completed_called());
+
+  FinishRequestSuccessfully();
+}
+
+TEST_F(ThrottlingResourceHandlerTest, Async) {
+  throttle1_->set_defer_on_will_start_request(true);
+  throttle1_->set_defer_on_will_redirect_request(true);
+  throttle1_->set_defer_on_will_process_response(true);
+
+  throttle2_->set_defer_on_will_start_request(true);
+  throttle2_->set_defer_on_will_redirect_request(true);
+  throttle2_->set_defer_on_will_process_response(true);
+
+  ASSERT_EQ(MockResourceLoader::Status::CALLBACK_PENDING,
+            mock_loader_->OnWillStart(GURL(kInitialUrl)));
+  EXPECT_EQ(1, throttle1_->will_start_request_called());
+  EXPECT_EQ(0, throttle2_->will_start_request_called());
+
+  throttle1_->Resume();
+  EXPECT_EQ(1, throttle2_->will_start_request_called());
+  EXPECT_EQ(0, test_handler_->on_will_start_called());
+  ASSERT_EQ(MockResourceLoader::Status::CALLBACK_PENDING,
+            mock_loader_->status());
+
+  throttle2_->Resume();
+  EXPECT_EQ(1, test_handler_->on_will_start_called());
+  ASSERT_EQ(MockResourceLoader::Status::IDLE, mock_loader_->status());
+
+  EXPECT_EQ(0, throttle1_->will_redirect_request_called());
+  net::RedirectInfo redirect_info;
+  redirect_info.status_code = 301;
+  redirect_info.new_url = GURL(kRedirectUrl);
+  ASSERT_EQ(
+      MockResourceLoader::Status::CALLBACK_PENDING,
+      mock_loader_->OnRequestRedirected(redirect_info, new ResourceResponse()));
+  EXPECT_EQ(1, throttle1_->will_redirect_request_called());
+  EXPECT_EQ(0, throttle2_->will_redirect_request_called());
+
+  throttle1_->Resume();
+  EXPECT_EQ(1, throttle2_->will_redirect_request_called());
+  EXPECT_EQ(0, test_handler_->on_request_redirected_called());
+  ASSERT_EQ(MockResourceLoader::Status::CALLBACK_PENDING,
+            mock_loader_->status());
+
+  throttle2_->Resume();
+  EXPECT_EQ(1, test_handler_->on_request_redirected_called());
+  ASSERT_EQ(MockResourceLoader::Status::IDLE, mock_loader_->status());
+
+  EXPECT_EQ(0, throttle1_->will_process_response_called());
+  ASSERT_EQ(MockResourceLoader::Status::CALLBACK_PENDING,
+            mock_loader_->OnResponseStarted(new ResourceResponse()));
+  EXPECT_EQ(1, throttle1_->will_process_response_called());
+  EXPECT_EQ(0, throttle2_->will_process_response_called());
+
+  throttle1_->Resume();
+  EXPECT_EQ(1, throttle2_->will_process_response_called());
+  EXPECT_EQ(0, test_handler_->on_response_started_called());
+  ASSERT_EQ(MockResourceLoader::Status::CALLBACK_PENDING,
+            mock_loader_->status());
+
+  throttle2_->Resume();
+  EXPECT_EQ(1, test_handler_->on_request_redirected_called());
+  EXPECT_EQ(1, test_handler_->on_response_started_called());
+  EXPECT_EQ(0, test_handler_->on_read_completed_called());
+  ASSERT_EQ(MockResourceLoader::Status::IDLE, mock_loader_->status());
+
+  FinishRequestSuccessfully();
+}
+
+// For a given method (WillStartRequest, WillRedirectRequest,
+// WillProcessResponse), each of the two throttles can cancel asynchronously or
+// synchronously, and the second throttle can cancel synchronously or
+// asynchronously after the first throttle completes synchronously or
+// asynchronously, for a total of 6 combinations.  However:

[Randy Smith (Not in Mondays), 2016/12/20 22:16:42]

This comment is true if all that is being tested is the cancel case; I think it
would be clearer if that was explicitly called out in the comment.

[mmenke, 2017/01/04 22:02:29]

Done.

+// 1)  Whenever the second throttle cancels asynchronously, it doesn't matter if
+// the first one completed synchronously or asynchronously, the state when it
+// cancels is the same.
+// 2)  The second cancelling asynchronously is much like the first one
+// cancelling asynchronously, so isn't worth testing individually.
+// 3)  Similarly, the second cancelling synchronously after the first one
+// completes synchronously doesn't really add anything to the first cancelling
+// synchronously.
+// So that leaves 3 interesting test cases for each of the three points
+// throttles can cancel.
+
+TEST_F(ThrottlingResourceHandlerTest, FirstThrottleSyncCancelOnWillStart) {
+  throttle1_->set_cancel_on_will_start_request(true);
+
+  ASSERT_EQ(MockResourceLoader::Status::CANCELED,
+            mock_loader_->OnWillStart(GURL(kInitialUrl)));
+  EXPECT_EQ(1, throttle1_->will_start_request_called());
+  EXPECT_EQ(0, throttle2_->will_start_request_called());
+  EXPECT_EQ(0, test_handler_->on_will_start_called());
+
+  ASSERT_EQ(MockResourceLoader::Status::IDLE,

[Randy Smith (Not in Mondays), 2016/12/20 22:16:41]

Worth a comment that this the the "URLRequest" responding to being cancelled? 
Given that it's part of the protocol I could imagine us changing in the future,
leaving breadcrumbs as to how to change the code might be worthwhile.  (Just an
idea, not pushing it.)

[mmenke, 2017/01/04 22:02:29]

Done.

+            mock_loader_->OnResponseCompleted(
+                net::URLRequestStatus::FromError(net::ERR_UNEXPECTED)));
+
+  EXPECT_EQ(1, throttle1_->will_start_request_called());
+  EXPECT_EQ(0, throttle1_->will_redirect_request_called());
+  EXPECT_EQ(0, throttle1_->will_process_response_called());
+
+  EXPECT_EQ(0, throttle2_->will_start_request_called());
+  EXPECT_EQ(0, throttle2_->will_redirect_request_called());
+  EXPECT_EQ(0, throttle2_->will_process_response_called());
+
+  EXPECT_EQ(0, test_handler_->on_will_start_called());
+  EXPECT_EQ(0, test_handler_->on_request_redirected_called());
+  EXPECT_EQ(0, test_handler_->on_response_started_called());
+  EXPECT_EQ(1, test_handler_->on_response_completed_called());

[Randy Smith (Not in Mondays), 2016/12/20 22:16:42]

I wonder if it's worthwhile putting in a helper routine that expects that
nothing's changed except for the test_handler_->on_response_compelted_called()
before/after the OnResponseCompleted(ERR_UNEXPECTED) call?  It seems like that's
a conceptually clean thing to assert, and it would save a lot of code.

[mmenke, 2017/01/04 22:02:29]

TestHandler already does that, but I'm not sure that saves us anything - that
doesn't catch the case that OnWillStart was unexpected called before
OnResponseCompleted was called in this test, for instance.

TestHandler does have enough checks that if on_will_start_called is 0, we don't
need to check request_redirected or response_started (And TestThrottles have the
same property for will_start_request_called() and the next two), but seemed most
readable and least regression-prone (When copying/pasting to make new tests) to
just keep all 10 checks at the end of every request.

[Randy Smith (Not in Mondays), 2017/01/11 19:57:15]

Acknowledged.

+}
+
+TEST_F(ThrottlingResourceHandlerTest, FirstThrottleAsyncCancelOnWillStart) {
+  throttle1_->set_defer_on_will_start_request(true);
+
+  ASSERT_EQ(MockResourceLoader::Status::CALLBACK_PENDING,
+            mock_loader_->OnWillStart(GURL(kInitialUrl)));
+  EXPECT_EQ(1, throttle1_->will_start_request_called());
+  EXPECT_EQ(0, throttle2_->will_start_request_called());
+  EXPECT_EQ(0, test_handler_->on_will_start_called());
+
+  throttle1_->CancelWithError(net::ERR_UNEXPECTED);
+  EXPECT_EQ(1, throttle1_->will_start_request_called());
+  EXPECT_EQ(0, throttle2_->will_start_request_called());
+  EXPECT_EQ(0, test_handler_->on_will_start_called());
+  ASSERT_EQ(MockResourceLoader::Status::CANCELED, mock_loader_->status());
+
+  ASSERT_EQ(MockResourceLoader::Status::IDLE,
+            mock_loader_->OnResponseCompleted(
+                net::URLRequestStatus::FromError(net::ERR_UNEXPECTED)));
+
+  EXPECT_EQ(1, throttle1_->will_start_request_called());
+  EXPECT_EQ(0, throttle1_->will_redirect_request_called());
+  EXPECT_EQ(0, throttle1_->will_process_response_called());
+
+  EXPECT_EQ(0, throttle2_->will_start_request_called());
+  EXPECT_EQ(0, throttle2_->will_redirect_request_called());
+  EXPECT_EQ(0, throttle2_->will_process_response_called());
+
+  EXPECT_EQ(0, test_handler_->on_will_start_called());
+  EXPECT_EQ(0, test_handler_->on_request_redirected_called());
+  EXPECT_EQ(0, test_handler_->on_response_started_called());
+  EXPECT_EQ(1, test_handler_->on_response_completed_called());
+}
+
+// The first throttle also defers and then resumes the request.

[Randy Smith (Not in Mondays), 2016/12/20 22:16:41]

I presume this is because that's a "more complex" case than synchronously
completing?

[mmenke, 2017/01/04 22:02:29]

It's so that it's a sync cancel with ThrottlingResourceHandler::Resume() at the
top of the callstack instead of ThrottlingResourceHandler::OnWillStart(), like
the test case where the first one cancels synchronously.  Added a comment about
that to all 3 of these tests.  (This is somewhat hinted at by the long comment
before these tests, but not directly stated - elaborated there, too)

I think we definitely need tests for sync cancel on Resume() case.  I can add 3
tests for second throttle cancel sync cancel after first throttle sync succeeds,
just didn't add them because I wasn't sure how useful they'd be, and because
each of these tests is huge.  :(

[Randy Smith (Not in Mondays), 2017/01/11 19:57:15]

After several flip-flops, I agree with you--the different is in the code above
the ThrottlingResourceHandler::On* routines, and there are strictly more such
routines in the callstack in the Resume case.  Ok.

+TEST_F(ThrottlingResourceHandlerTest, SecondThrottleSyncCancelOnWillStart) {
+  throttle1_->set_defer_on_will_start_request(true);
+  throttle2_->set_cancel_on_will_start_request(true);
+
+  ASSERT_EQ(MockResourceLoader::Status::CALLBACK_PENDING,
+            mock_loader_->OnWillStart(GURL(kInitialUrl)));
+  EXPECT_EQ(1, throttle1_->will_start_request_called());
+  EXPECT_EQ(0, throttle2_->will_start_request_called());
+  EXPECT_EQ(0, test_handler_->on_will_start_called());
+
+  throttle1_->Resume();
+  EXPECT_EQ(1, throttle1_->will_start_request_called());
+  EXPECT_EQ(1, throttle2_->will_start_request_called());
+  EXPECT_EQ(0, test_handler_->on_will_start_called());
+  ASSERT_EQ(MockResourceLoader::Status::CANCELED, mock_loader_->status());
+
+  ASSERT_EQ(MockResourceLoader::Status::IDLE,
+            mock_loader_->OnResponseCompleted(
+                net::URLRequestStatus::FromError(net::ERR_UNEXPECTED)));
+
+  EXPECT_EQ(1, throttle1_->will_start_request_called());
+  EXPECT_EQ(0, throttle1_->will_redirect_request_called());
+  EXPECT_EQ(0, throttle1_->will_process_response_called());
+
+  EXPECT_EQ(1, throttle2_->will_start_request_called());
+  EXPECT_EQ(0, throttle2_->will_redirect_request_called());
+  EXPECT_EQ(0, throttle2_->will_process_response_called());
+
+  EXPECT_EQ(0, test_handler_->on_will_start_called());
+  EXPECT_EQ(0, test_handler_->on_request_redirected_called());
+  EXPECT_EQ(0, test_handler_->on_response_started_called());
+  EXPECT_EQ(1, test_handler_->on_response_completed_called());
+}
+
+TEST_F(ThrottlingResourceHandlerTest,
+       FirstThrottleSyncCancelOnRequestRedirected) {
+  throttle1_->set_cancel_on_will_redirect_request(true);
+
+  ASSERT_EQ(MockResourceLoader::Status::IDLE,
+            mock_loader_->OnWillStart(GURL(kInitialUrl)));
+
+  net::RedirectInfo redirect_info;
+  redirect_info.status_code = 301;
+  redirect_info.new_url = GURL(kRedirectUrl);
+  ASSERT_EQ(
+      MockResourceLoader::Status::CANCELED,
+      mock_loader_->OnRequestRedirected(redirect_info, new ResourceResponse()));
+  EXPECT_EQ(1, throttle1_->will_redirect_request_called());
+  EXPECT_EQ(0, throttle2_->will_redirect_request_called());
+  EXPECT_EQ(0, test_handler_->on_request_redirected_called());
+
+  ASSERT_EQ(MockResourceLoader::Status::IDLE,
+            mock_loader_->OnResponseCompleted(
+                net::URLRequestStatus::FromError(net::ERR_UNEXPECTED)));
+
+  EXPECT_EQ(1, throttle1_->will_start_request_called());
+  EXPECT_EQ(1, throttle1_->will_redirect_request_called());
+  EXPECT_EQ(0, throttle1_->will_process_response_called());
+
+  EXPECT_EQ(1, throttle2_->will_start_request_called());
+  EXPECT_EQ(0, throttle2_->will_redirect_request_called());
+  EXPECT_EQ(0, throttle2_->will_process_response_called());
+
+  EXPECT_EQ(1, test_handler_->on_will_start_called());
+  EXPECT_EQ(0, test_handler_->on_request_redirected_called());
+  EXPECT_EQ(0, test_handler_->on_response_started_called());
+  EXPECT_EQ(1, test_handler_->on_response_completed_called());
+}
+
+TEST_F(ThrottlingResourceHandlerTest,
+       FirstThrottleAsyncCancelOnRequestRedirected) {
+  throttle1_->set_defer_on_will_redirect_request(true);
+
+  ASSERT_EQ(MockResourceLoader::Status::IDLE,
+            mock_loader_->OnWillStart(GURL(kInitialUrl)));
+
+  net::RedirectInfo redirect_info;
+  redirect_info.status_code = 301;
+  redirect_info.new_url = GURL(kRedirectUrl);
+  ASSERT_EQ(
+      MockResourceLoader::Status::CALLBACK_PENDING,
+      mock_loader_->OnRequestRedirected(redirect_info, new ResourceResponse()));
+
+  throttle1_->CancelWithError(net::ERR_UNEXPECTED);
+  EXPECT_EQ(1, throttle1_->will_redirect_request_called());
+  EXPECT_EQ(0, throttle2_->will_redirect_request_called());
+  EXPECT_EQ(0, test_handler_->on_request_redirected_called());
+  ASSERT_EQ(MockResourceLoader::Status::CANCELED, mock_loader_->status());
+
+  ASSERT_EQ(MockResourceLoader::Status::IDLE,
+            mock_loader_->OnResponseCompleted(
+                net::URLRequestStatus::FromError(net::ERR_UNEXPECTED)));
+
+  EXPECT_EQ(1, throttle1_->will_start_request_called());
+  EXPECT_EQ(1, throttle1_->will_redirect_request_called());
+  EXPECT_EQ(0, throttle1_->will_process_response_called());
+
+  EXPECT_EQ(1, throttle2_->will_start_request_called());
+  EXPECT_EQ(0, throttle2_->will_redirect_request_called());
+  EXPECT_EQ(0, throttle2_->will_process_response_called());
+
+  EXPECT_EQ(1, test_handler_->on_will_start_called());
+  EXPECT_EQ(0, test_handler_->on_request_redirected_called());
+  EXPECT_EQ(0, test_handler_->on_response_started_called());
+  EXPECT_EQ(1, test_handler_->on_response_completed_called());
+}
+
+// The first throttle also defers and then resumes the request.
+TEST_F(ThrottlingResourceHandlerTest,
+       SecondThrottleSyncCancelOnRequestRedirected) {
+  throttle1_->set_defer_on_will_redirect_request(true);
+  throttle2_->set_cancel_on_will_redirect_request(true);
+
+  ASSERT_EQ(MockResourceLoader::Status::IDLE,
+            mock_loader_->OnWillStart(GURL(kInitialUrl)));
+
+  net::RedirectInfo redirect_info;
+  redirect_info.status_code = 301;
+  redirect_info.new_url = GURL(kRedirectUrl);
+  ASSERT_EQ(
+      MockResourceLoader::Status::CALLBACK_PENDING,
+      mock_loader_->OnRequestRedirected(redirect_info, new ResourceResponse()));
+
+  throttle1_->Resume();
+  EXPECT_EQ(1, throttle1_->will_redirect_request_called());
+  EXPECT_EQ(1, throttle2_->will_redirect_request_called());
+  EXPECT_EQ(0, test_handler_->on_request_redirected_called());
+  ASSERT_EQ(MockResourceLoader::Status::CANCELED, mock_loader_->status());
+
+  ASSERT_EQ(MockResourceLoader::Status::IDLE,
+            mock_loader_->OnResponseCompleted(
+                net::URLRequestStatus::FromError(net::ERR_UNEXPECTED)));
+
+  EXPECT_EQ(1, throttle1_->will_start_request_called());
+  EXPECT_EQ(1, throttle1_->will_redirect_request_called());
+  EXPECT_EQ(0, throttle1_->will_process_response_called());
+
+  EXPECT_EQ(1, throttle2_->will_start_request_called());
+  EXPECT_EQ(1, throttle2_->will_redirect_request_called());
+  EXPECT_EQ(0, throttle2_->will_process_response_called());
+
+  EXPECT_EQ(1, test_handler_->on_will_start_called());
+  EXPECT_EQ(0, test_handler_->on_request_redirected_called());
+  EXPECT_EQ(0, test_handler_->on_response_started_called());
+  EXPECT_EQ(1, test_handler_->on_response_completed_called());
+}
+
+TEST_F(ThrottlingResourceHandlerTest,
+       FirstThrottleSyncCancelOnWillProcessResponse) {
+  throttle1_->set_cancel_on_will_process_response(true);
+
+  ASSERT_EQ(MockResourceLoader::Status::IDLE,
+            mock_loader_->OnWillStart(GURL(kInitialUrl)));
+
+  ASSERT_EQ(MockResourceLoader::Status::CANCELED,
+            mock_loader_->OnResponseStarted(new ResourceResponse()));
+  EXPECT_EQ(1, throttle1_->will_process_response_called());
+  EXPECT_EQ(0, throttle2_->will_process_response_called());
+  EXPECT_EQ(0, test_handler_->on_response_started_called());
+
+  ASSERT_EQ(MockResourceLoader::Status::IDLE,
+            mock_loader_->OnResponseCompleted(
+                net::URLRequestStatus::FromError(net::ERR_UNEXPECTED)));
+
+  EXPECT_EQ(1, throttle1_->will_start_request_called());
+  EXPECT_EQ(0, throttle1_->will_redirect_request_called());
+  EXPECT_EQ(1, throttle1_->will_process_response_called());
+
+  EXPECT_EQ(1, throttle2_->will_start_request_called());
+  EXPECT_EQ(0, throttle2_->will_redirect_request_called());
+  EXPECT_EQ(0, throttle2_->will_process_response_called());
+
+  EXPECT_EQ(1, test_handler_->on_will_start_called());
+  EXPECT_EQ(0, test_handler_->on_request_redirected_called());
+  EXPECT_EQ(0, test_handler_->on_response_started_called());
+  EXPECT_EQ(1, test_handler_->on_response_completed_called());
+}
+
+TEST_F(ThrottlingResourceHandlerTest,
+       FirstThrottleAsyncCancelOnWillProcessResponse) {
+  throttle1_->set_defer_on_will_process_response(true);
+
+  ASSERT_EQ(MockResourceLoader::Status::IDLE,
+            mock_loader_->OnWillStart(GURL(kInitialUrl)));
+
+  ASSERT_EQ(MockResourceLoader::Status::CALLBACK_PENDING,
+            mock_loader_->OnResponseStarted(new ResourceResponse()));
+  EXPECT_EQ(1, throttle1_->will_process_response_called());
+  EXPECT_EQ(0, throttle2_->will_process_response_called());
+  EXPECT_EQ(0, test_handler_->on_response_started_called());
+
+  throttle1_->CancelWithError(net::ERR_UNEXPECTED);
+  EXPECT_EQ(1, throttle1_->will_process_response_called());
+  EXPECT_EQ(0, throttle2_->will_process_response_called());
+  EXPECT_EQ(0, test_handler_->on_response_started_called());
+  ASSERT_EQ(MockResourceLoader::Status::CANCELED, mock_loader_->status());
+
+  ASSERT_EQ(MockResourceLoader::Status::IDLE,
+            mock_loader_->OnResponseCompleted(
+                net::URLRequestStatus::FromError(net::ERR_UNEXPECTED)));
+
+  EXPECT_EQ(1, throttle1_->will_start_request_called());
+  EXPECT_EQ(0, throttle1_->will_redirect_request_called());
+  EXPECT_EQ(1, throttle1_->will_process_response_called());
+
+  EXPECT_EQ(1, throttle2_->will_start_request_called());
+  EXPECT_EQ(0, throttle2_->will_redirect_request_called());
+  EXPECT_EQ(0, throttle2_->will_process_response_called());
+
+  EXPECT_EQ(1, test_handler_->on_will_start_called());
+  EXPECT_EQ(0, test_handler_->on_request_redirected_called());
+  EXPECT_EQ(0, test_handler_->on_response_started_called());
+  EXPECT_EQ(1, test_handler_->on_response_completed_called());
+}
+
+// The first throttle also defers and then resumes the request.
+TEST_F(ThrottlingResourceHandlerTest,
+       SecondThrottleSyncCancelOnWillProcessResponse) {
+  throttle1_->set_defer_on_will_process_response(true);
+  throttle2_->set_cancel_on_will_process_response(true);
+
+  ASSERT_EQ(MockResourceLoader::Status::IDLE,
+            mock_loader_->OnWillStart(GURL(kInitialUrl)));
+
+  ASSERT_EQ(MockResourceLoader::Status::CALLBACK_PENDING,
+            mock_loader_->OnResponseStarted(new ResourceResponse()));
+  EXPECT_EQ(1, throttle1_->will_process_response_called());
+  EXPECT_EQ(0, throttle2_->will_process_response_called());
+  EXPECT_EQ(0, test_handler_->on_response_started_called());
+
+  throttle1_->Resume();
+  EXPECT_EQ(1, throttle1_->will_process_response_called());
+  EXPECT_EQ(1, throttle2_->will_process_response_called());
+  EXPECT_EQ(0, test_handler_->on_response_started_called());
+  ASSERT_EQ(MockResourceLoader::Status::CANCELED, mock_loader_->status());
+
+  ASSERT_EQ(MockResourceLoader::Status::IDLE,
+            mock_loader_->OnResponseCompleted(
+                net::URLRequestStatus::FromError(net::ERR_UNEXPECTED)));
+
+  EXPECT_EQ(1, throttle1_->will_start_request_called());
+  EXPECT_EQ(0, throttle1_->will_redirect_request_called());
+  EXPECT_EQ(1, throttle1_->will_process_response_called());
+
+  EXPECT_EQ(1, throttle2_->will_start_request_called());
+  EXPECT_EQ(0, throttle2_->will_redirect_request_called());
+  EXPECT_EQ(1, throttle2_->will_process_response_called());
+
+  EXPECT_EQ(1, test_handler_->on_will_start_called());
+  EXPECT_EQ(0, test_handler_->on_request_redirected_called());
+  EXPECT_EQ(0, test_handler_->on_response_started_called());
+  EXPECT_EQ(1, test_handler_->on_response_completed_called());
+}
+
+TEST_F(ThrottlingResourceHandlerTest, OutOfBandCancelBeforeWillStart) {

[Randy Smith (Not in Mondays), 2016/12/20 22:16:41]

As noted elsewhere, I'd like to understand the OOBC from throttles use cases in
the current Chromium code; it seems extra weird to me, and part of me would
rather move towards forbidding it than thoroughly testing it.

[Randy Smith (Not in Mondays), 2017/01/11 19:57:15]

As noted elsewhere, accepted for this CL.

+  throttle1_->CancelWithError(net::ERR_UNEXPECTED);
+  EXPECT_EQ(MockResourceLoader::Status::CANCELED, mock_loader_->status());
+  EXPECT_EQ(net::ERR_UNEXPECTED, mock_loader_->error_code());
+
+  EXPECT_EQ(MockResourceLoader::Status::IDLE,
+            mock_loader_->OnResponseCompleted(
+                net::URLRequestStatus::FromError(net::ERR_UNEXPECTED)));
+
+  EXPECT_EQ(0, throttle1_->will_start_request_called());
+  EXPECT_EQ(0, throttle1_->will_redirect_request_called());
+  EXPECT_EQ(0, throttle1_->will_process_response_called());
+
+  EXPECT_EQ(0, throttle2_->will_start_request_called());
+  EXPECT_EQ(0, throttle2_->will_redirect_request_called());
+  EXPECT_EQ(0, throttle2_->will_process_response_called());
+
+  EXPECT_EQ(0, test_handler_->on_will_start_called());
+  EXPECT_EQ(0, test_handler_->on_request_redirected_called());
+  EXPECT_EQ(0, test_handler_->on_response_started_called());
+  EXPECT_EQ(1, test_handler_->on_response_completed_called());
+}
+
+TEST_F(ThrottlingResourceHandlerTest, OutOfBandCancelAfterWillStart) {
+  EXPECT_EQ(MockResourceLoader::Status::IDLE,
+            mock_loader_->OnWillStart(GURL(kInitialUrl)));
+
+  throttle1_->CancelWithError(net::ERR_UNEXPECTED);
+  EXPECT_EQ(MockResourceLoader::Status::CANCELED, mock_loader_->status());
+  EXPECT_EQ(net::ERR_UNEXPECTED, mock_loader_->error_code());
+
+  EXPECT_EQ(MockResourceLoader::Status::IDLE,
+            mock_loader_->OnResponseCompleted(
+                net::URLRequestStatus::FromError(net::ERR_UNEXPECTED)));
+
+  EXPECT_EQ(1, throttle1_->will_start_request_called());
+  EXPECT_EQ(0, throttle1_->will_redirect_request_called());
+  EXPECT_EQ(0, throttle1_->will_process_response_called());
+
+  EXPECT_EQ(1, throttle2_->will_start_request_called());
+  EXPECT_EQ(0, throttle2_->will_redirect_request_called());
+  EXPECT_EQ(0, throttle2_->will_process_response_called());
+
+  EXPECT_EQ(1, test_handler_->on_will_start_called());
+  EXPECT_EQ(0, test_handler_->on_request_redirected_called());
+  EXPECT_EQ(0, test_handler_->on_response_started_called());
+  EXPECT_EQ(1, test_handler_->on_response_completed_called());
+}
+
+TEST_F(ThrottlingResourceHandlerTest, OutOfBandCancelAfterRequestRedirected) {
+  EXPECT_EQ(MockResourceLoader::Status::IDLE,
+            mock_loader_->OnWillStart(GURL(kInitialUrl)));
+  net::RedirectInfo redirect_info;
+  redirect_info.status_code = 301;
+  redirect_info.new_url = GURL(kRedirectUrl);
+  EXPECT_EQ(
+      MockResourceLoader::Status::IDLE,
+      mock_loader_->OnRequestRedirected(redirect_info, new ResourceResponse()));
+
+  throttle1_->CancelWithError(net::ERR_UNEXPECTED);
+  EXPECT_EQ(MockResourceLoader::Status::CANCELED, mock_loader_->status());
+  EXPECT_EQ(net::ERR_UNEXPECTED, mock_loader_->error_code());
+
+  EXPECT_EQ(MockResourceLoader::Status::IDLE,
+            mock_loader_->OnResponseCompleted(
+                net::URLRequestStatus::FromError(net::ERR_UNEXPECTED)));
+
+  EXPECT_EQ(1, throttle1_->will_start_request_called());
+  EXPECT_EQ(1, throttle1_->will_redirect_request_called());
+  EXPECT_EQ(0, throttle1_->will_process_response_called());
+
+  EXPECT_EQ(1, throttle2_->will_start_request_called());
+  EXPECT_EQ(1, throttle2_->will_redirect_request_called());
+  EXPECT_EQ(0, throttle2_->will_process_response_called());
+
+  EXPECT_EQ(1, test_handler_->on_will_start_called());
+  EXPECT_EQ(1, test_handler_->on_request_redirected_called());
+  EXPECT_EQ(0, test_handler_->on_response_started_called());
+  EXPECT_EQ(1, test_handler_->on_response_completed_called());
+}
+
+TEST_F(ThrottlingResourceHandlerTest, OutOfBandCancelAfterResponseStarted) {
+  EXPECT_EQ(MockResourceLoader::Status::IDLE,
+            mock_loader_->OnWillStart(GURL(kInitialUrl)));
+  net::RedirectInfo redirect_info;
+  redirect_info.status_code = 301;
+  redirect_info.new_url = GURL(kRedirectUrl);
+  EXPECT_EQ(
+      MockResourceLoader::Status::IDLE,
+      mock_loader_->OnRequestRedirected(redirect_info, new ResourceResponse()));
+  EXPECT_EQ(MockResourceLoader::Status::IDLE,
+            mock_loader_->OnResponseStarted(new ResourceResponse()));
+
+  throttle1_->CancelWithError(net::ERR_UNEXPECTED);
+  EXPECT_EQ(MockResourceLoader::Status::CANCELED, mock_loader_->status());
+  EXPECT_EQ(net::ERR_UNEXPECTED, mock_loader_->error_code());
+
+  EXPECT_EQ(MockResourceLoader::Status::IDLE,
+            mock_loader_->OnResponseCompleted(
+                net::URLRequestStatus::FromError(net::ERR_UNEXPECTED)));
+
+  EXPECT_EQ(1, throttle1_->will_start_request_called());
+  EXPECT_EQ(1, throttle1_->will_redirect_request_called());
+  EXPECT_EQ(1, throttle1_->will_process_response_called());
+
+  EXPECT_EQ(1, throttle2_->will_start_request_called());
+  EXPECT_EQ(1, throttle2_->will_redirect_request_called());
+  EXPECT_EQ(1, throttle2_->will_process_response_called());
+
+  EXPECT_EQ(1, test_handler_->on_will_start_called());
+  EXPECT_EQ(1, test_handler_->on_request_redirected_called());
+  EXPECT_EQ(1, test_handler_->on_response_started_called());
+  EXPECT_EQ(1, test_handler_->on_response_completed_called());
+}
+
+TEST_F(ThrottlingResourceHandlerTest, OutOfBandCancelAndResumeDuringWillStart) {
+  throttle1_->set_defer_on_will_start_request(1);
+  EXPECT_EQ(MockResourceLoader::Status::CALLBACK_PENDING,
+            mock_loader_->OnWillStart(GURL(kInitialUrl)));
+
+  // |throttle2_| cancels.
+  throttle2_->CancelWithError(net::ERR_UNEXPECTED);
+  EXPECT_EQ(MockResourceLoader::Status::CANCELED, mock_loader_->status());
+  EXPECT_EQ(net::ERR_UNEXPECTED, mock_loader_->error_code());
+
+  // |throttle1_|, blissfully unaware of cancellation, resumes the request.
+  throttle1_->Resume();
+
+  EXPECT_EQ(MockResourceLoader::Status::IDLE,
+            mock_loader_->OnResponseCompleted(
+                net::URLRequestStatus::FromError(net::ERR_UNEXPECTED)));
+
+  EXPECT_EQ(1, throttle1_->will_start_request_called());
+  EXPECT_EQ(0, throttle1_->will_redirect_request_called());
+  EXPECT_EQ(0, throttle1_->will_process_response_called());
+
+  EXPECT_EQ(0, throttle2_->will_start_request_called());
+  EXPECT_EQ(0, throttle2_->will_redirect_request_called());
+  EXPECT_EQ(0, throttle2_->will_process_response_called());
+
+  EXPECT_EQ(0, test_handler_->on_will_start_called());
+  EXPECT_EQ(0, test_handler_->on_request_redirected_called());
+  EXPECT_EQ(0, test_handler_->on_response_started_called());
+  EXPECT_EQ(1, test_handler_->on_response_completed_called());
+}
+
+TEST_F(ThrottlingResourceHandlerTest, DoubleCancelDuringWillStart) {
+  throttle1_->set_defer_on_will_start_request(1);
+  EXPECT_EQ(MockResourceLoader::Status::CALLBACK_PENDING,
+            mock_loader_->OnWillStart(GURL(kInitialUrl)));
+
+  // |throttle2_| cancels.
+  throttle2_->CancelWithError(net::ERR_UNEXPECTED);
+  EXPECT_EQ(MockResourceLoader::Status::CANCELED, mock_loader_->status());
+  EXPECT_EQ(net::ERR_UNEXPECTED, mock_loader_->error_code());
+
+  // |throttle1_|, unaware of the cancellation, also cancels.
+  throttle1_->CancelWithError(net::ERR_FAILED);
+  EXPECT_EQ(MockResourceLoader::Status::CANCELED, mock_loader_->status());
+  EXPECT_EQ(net::ERR_UNEXPECTED, mock_loader_->error_code());
+
+  EXPECT_EQ(MockResourceLoader::Status::IDLE,
+            mock_loader_->OnResponseCompleted(
+                net::URLRequestStatus::FromError(net::ERR_UNEXPECTED)));
+
+  EXPECT_EQ(1, throttle1_->will_start_request_called());
+  EXPECT_EQ(0, throttle1_->will_redirect_request_called());
+  EXPECT_EQ(0, throttle1_->will_process_response_called());
+
+  EXPECT_EQ(0, throttle2_->will_start_request_called());
+  EXPECT_EQ(0, throttle2_->will_redirect_request_called());
+  EXPECT_EQ(0, throttle2_->will_process_response_called());
+
+  EXPECT_EQ(0, test_handler_->on_will_start_called());
+  EXPECT_EQ(0, test_handler_->on_request_redirected_called());
+  EXPECT_EQ(0, test_handler_->on_response_started_called());
+  EXPECT_EQ(1, test_handler_->on_response_completed_called());
+}
+
+}  // namespace
+}  // namespace content