11 files changed, 1127 insertions, 2 deletions

diff --git a/net/url_request/url_request_http_job.cc b/net/url_request/url_request_http_job.cc
index f00f490..826f635 100644
--- a/net/url_request/url_request_http_job.cc
+++ b/net/url_request/url_request_http_job.cc
@@ -33,6 +33,8 @@
 #include "net/url_request/url_request_context.h"
 #include "net/url_request/url_request_error_job.h"
 #include "net/url_request/url_request_redirect_job.h"
+#include "net/url_request/url_request_throttler_header_adapter.h"
+#include "net/url_request/url_request_throttler_manager.h"
 
 static const char kAvailDictionaryHeader[] = "Avail-Dictionary";
 
@@ -91,6 +93,8 @@ URLRequestHttpJob::URLRequestHttpJob(URLRequest* request)
           this, &URLRequestHttpJob::OnReadCompleted)),
       read_in_progress_(false),
       transaction_(NULL),
+      throttling_entry_(net::URLRequestThrottlerManager::GetInstance()->
+          RegisterRequestUrl(request->url())),
       sdch_dictionary_advertised_(false),
       sdch_test_activated_(false),
       sdch_test_control_(false),
@@ -569,6 +573,12 @@ void URLRequestHttpJob::NotifyHeadersComplete() {
   // also need this info.
   is_cached_content_ = response_info_->was_cached;
 
+  if (!is_cached_content_) {
+    net::URLRequestThrottlerHeaderAdapter response_adapter(
+        response_info_->headers);
+    throttling_entry_->UpdateWithResponse(&response_adapter);
+  }
+
   ProcessStrictTransportSecurityHeader();
 
   if (SdchManager::Global() &&
@@ -618,6 +628,7 @@ void URLRequestHttpJob::StartTransaction() {
   // with auth provided by username_ and password_.
 
   int rv;
+
   if (transaction_.get()) {
     rv = transaction_->RestartWithAuth(username_, password_, &start_callback_);
     username_.clear();
@@ -629,8 +640,13 @@ void URLRequestHttpJob::StartTransaction() {
     rv = request_->context()->http_transaction_factory()->CreateTransaction(
         &transaction_);
     if (rv == net::OK) {
-      rv = transaction_->Start(
-          &request_info_, &start_callback_, request_->net_log());
+      if (!throttling_entry_->IsDuringExponentialBackoff()) {
+        rv = transaction_->Start(
+            &request_info_, &start_callback_, request_->net_log());
+      } else {
+        // Special error code for the exponential back-off module.
+        rv = net::ERR_TEMPORARILY_THROTTLED;
+      }
       // Make sure the context is alive for the duration of the
       // transaction.
       context_ = request_->context();
diff --git a/net/url_request/url_request_http_job.h b/net/url_request/url_request_http_job.h
index 431756a..c981047 100644
--- a/net/url_request/url_request_http_job.h
+++ b/net/url_request/url_request_http_job.h
@@ -15,6 +15,7 @@
 #include "net/base/completion_callback.h"
 #include "net/http/http_request_info.h"
 #include "net/url_request/url_request_job.h"
+#include "net/url_request/url_request_throttler_entry_interface.h"
 
 namespace net {
 class HttpResponseInfo;
@@ -112,6 +113,9 @@ class URLRequestHttpJob : public URLRequestJob {
 
   scoped_ptr<net::HttpTransaction> transaction_;
 
+  // This is used to supervise traffic and enforce exponential back-off.
+  scoped_refptr<net::URLRequestThrottlerEntryInterface> throttling_entry_;
+
   // Indicated if an SDCH dictionary was advertised, and hence an SDCH
   // compressed response is expected.  We use this to help detect (accidental?)
   // proxy corruption of a response, which sometimes marks SDCH content as
diff --git a/net/url_request/url_request_throttler_entry.cc b/net/url_request/url_request_throttler_entry.cc
new file mode 100644
index 0000000..4abb438
--- /dev/null
+++ b/net/url_request/url_request_throttler_entry.cc
@@ -0,0 +1,242 @@
+// Copyright (c) 2010 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 "net/url_request/url_request_throttler_entry.h"
+
+#include <cmath>
+
+#include "base/logging.h"
+#include "base/rand_util.h"
+#include "base/string_number_conversions.h"
+#include "net/url_request/url_request_throttler_header_interface.h"
+
+namespace net {
+
+const int URLRequestThrottlerEntry::kDefaultSlidingWindowPeriodMs = 2000;
+const int URLRequestThrottlerEntry::kDefaultMaxSendThreshold = 20;
+const int URLRequestThrottlerEntry::kDefaultInitialBackoffMs = 700;
+const int URLRequestThrottlerEntry::kDefaultAdditionalConstantMs = 100;
+const double URLRequestThrottlerEntry::kDefaultMultiplyFactor = 1.4;
+const double URLRequestThrottlerEntry::kDefaultJitterFactor = 0.4;
+const int URLRequestThrottlerEntry::kDefaultMaximumBackoffMs = 60 * 60 * 1000;
+const int URLRequestThrottlerEntry::kDefaultEntryLifetimeMs = 120000;
+const char URLRequestThrottlerEntry::kRetryHeaderName[] = "X-Retry-After";
+
+URLRequestThrottlerEntry::URLRequestThrottlerEntry()
+    : sliding_window_period_(
+          base::TimeDelta::FromMilliseconds(kDefaultSlidingWindowPeriodMs)),
+      max_send_threshold_(kDefaultMaxSendThreshold),
+      initial_backoff_ms_(kDefaultInitialBackoffMs),
+      additional_constant_ms_(kDefaultAdditionalConstantMs),
+      multiply_factor_(kDefaultMultiplyFactor),
+      jitter_factor_(kDefaultJitterFactor),
+      maximum_backoff_ms_(kDefaultMaximumBackoffMs),
+      entry_lifetime_ms_(kDefaultEntryLifetimeMs) {
+  Initialize();
+}
+
+URLRequestThrottlerEntry::URLRequestThrottlerEntry(
+    int sliding_window_period_ms,
+    int max_send_threshold,
+    int initial_backoff_ms,
+    int additional_constant_ms,
+    double multiply_factor,
+    double jitter_factor,
+    int maximum_backoff_ms)
+    : sliding_window_period_(
+          base::TimeDelta::FromMilliseconds(sliding_window_period_ms)),
+      max_send_threshold_(max_send_threshold),
+      initial_backoff_ms_(initial_backoff_ms),
+      additional_constant_ms_(additional_constant_ms),
+      multiply_factor_(multiply_factor),
+      jitter_factor_(jitter_factor),
+      maximum_backoff_ms_(maximum_backoff_ms),
+      entry_lifetime_ms_(-1) {
+  DCHECK_GT(sliding_window_period_ms, 0);
+  DCHECK_GT(max_send_threshold_, 0);
+  DCHECK_GE(initial_backoff_ms_, 0);
+  DCHECK_GE(additional_constant_ms_, 0);
+  DCHECK_GT(multiply_factor_, 0);
+  DCHECK_GE(jitter_factor_, 0);
+  DCHECK_LT(jitter_factor_, 1);
+  DCHECK_GE(maximum_backoff_ms_, 0);
+
+  Initialize();
+}
+
+URLRequestThrottlerEntry::~URLRequestThrottlerEntry() {
+}
+
+void URLRequestThrottlerEntry::Initialize() {
+  // Since this method is called by the constructors, GetTimeNow() (a virtual
+  // method) is not used.
+  exponential_backoff_release_time_ = base::TimeTicks::Now();
+  failure_count_ = 0;
+  latest_response_was_failure_ = false;
+
+  sliding_window_release_time_ = base::TimeTicks::Now();
+}
+
+bool URLRequestThrottlerEntry::IsDuringExponentialBackoff() const {
+  return exponential_backoff_release_time_ > GetTimeNow();
+}
+
+int64 URLRequestThrottlerEntry::ReserveSendingTimeForNextRequest(
+    const base::TimeTicks& earliest_time) {
+  base::TimeTicks now = GetTimeNow();
+  // If a lot of requests were successfully made recently,
+  // sliding_window_release_time_ may be greater than
+  // exponential_backoff_release_time_.
+  base::TimeTicks recommended_sending_time =
+      std::max(std::max(now, earliest_time),
+               std::max(exponential_backoff_release_time_,
+                        sliding_window_release_time_));
+
+  DCHECK(send_log_.empty() ||
+         recommended_sending_time >= send_log_.back());
+  // Log the new send event.
+  send_log_.push(recommended_sending_time);
+
+  sliding_window_release_time_ = recommended_sending_time;
+
+  // Drop the out-of-date events in the event list.
+  // We don't need to worry that the queue may become empty during this
+  // operation, since the last element is sliding_window_release_time_.
+  while ((send_log_.front() + sliding_window_period_ <=
+          sliding_window_release_time_) ||
+         send_log_.size() > static_cast<unsigned>(max_send_threshold_)) {
+    send_log_.pop();
+  }
+
+  // Check if there are too many send events in recent time.
+  if (send_log_.size() == static_cast<unsigned>(max_send_threshold_))
+    sliding_window_release_time_ = send_log_.front() + sliding_window_period_;
+
+  return (recommended_sending_time - now).InMillisecondsRoundedUp();
+}
+
+base::TimeTicks
+    URLRequestThrottlerEntry::GetExponentialBackoffReleaseTime() const {
+  return exponential_backoff_release_time_;
+}
+
+void URLRequestThrottlerEntry::UpdateWithResponse(
+    const URLRequestThrottlerHeaderInterface* response) {
+  if (response->GetResponseCode() >= 500) {
+    failure_count_++;
+    latest_response_was_failure_ = true;
+    exponential_backoff_release_time_ =
+        CalculateExponentialBackoffReleaseTime();
+  } else {
+    // We slowly decay the number of times delayed instead of resetting it to 0
+    // in order to stay stable if we received lots of requests with
+    // malformed bodies at the same time.
+    if (failure_count_ > 0)
+      failure_count_--;
+
+    latest_response_was_failure_ = false;
+
+    // The reason why we are not just cutting the release time to GetTimeNow()
+    // is on the one hand, it would unset delay put by our custom retry-after
+    // header and on the other we would like to push every request up to our
+    // "horizon" when dealing with multiple in-flight requests. Ex: If we send
+    // three requests and we receive 2 failures and 1 success. The success that
+    // follows those failures will not reset the release time, further requests
+    // will then need to wait the delay caused by the 2 failures.
+    exponential_backoff_release_time_ = std::max(
+        GetTimeNow(), exponential_backoff_release_time_);
+
+    std::string retry_header = response->GetNormalizedValue(kRetryHeaderName);
+    if (!retry_header.empty())
+      HandleCustomRetryAfter(retry_header);
+  }
+}
+
+bool URLRequestThrottlerEntry::IsEntryOutdated() const {
+  if (entry_lifetime_ms_ == -1)
+    return false;
+
+  base::TimeTicks now = GetTimeNow();
+
+  // If there are send events in the sliding window period, we still need this
+  // entry.
+  if (send_log_.size() > 0 &&
+      send_log_.back() + sliding_window_period_ > now) {
+    return false;
+  }
+
+  int64 unused_since_ms =
+      (now - exponential_backoff_release_time_).InMilliseconds();
+
+  // Release time is further than now, we are managing it.
+  if (unused_since_ms < 0)
+    return false;
+
+  // latest_response_was_failure_ is true indicates that the latest one or
+  // more requests encountered server errors or had malformed response bodies.
+  // In that case, we don't want to collect the entry unless it hasn't been used
+  // for longer than the maximum allowed back-off.
+  if (latest_response_was_failure_)
+    return unused_since_ms > std::max(maximum_backoff_ms_, entry_lifetime_ms_);
+
+  // Otherwise, consider the entry is outdated if it hasn't been used for the
+  // specified lifetime period.
+  return unused_since_ms > entry_lifetime_ms_;
+}
+
+void URLRequestThrottlerEntry::ReceivedContentWasMalformed() {
+  // For any response that is marked as malformed now, we have probably
+  // considered it as a success when receiving it and decreased the failure
+  // count by 1. As a result, we increase the failure count by 2 here to undo
+  // the effect and record a failure.
+  //
+  // Please note that this may lead to a larger failure count than expected,
+  // because we don't decrease the failure count for successful responses when
+  // it has already reached 0.
+  failure_count_ += 2;
+  latest_response_was_failure_ = true;
+  exponential_backoff_release_time_ = CalculateExponentialBackoffReleaseTime();
+}
+
+base::TimeTicks
+    URLRequestThrottlerEntry::CalculateExponentialBackoffReleaseTime() {
+  double delay = initial_backoff_ms_;
+  delay *= pow(multiply_factor_, failure_count_);
+  delay += additional_constant_ms_;
+  delay -= base::RandDouble() * jitter_factor_ * delay;
+
+  // Ensure that we do not exceed maximum delay.
+  int64 delay_int = static_cast<int64>(delay + 0.5);
+  delay_int = std::min(delay_int, static_cast<int64>(maximum_backoff_ms_));
+
+  return std::max(GetTimeNow() + base::TimeDelta::FromMilliseconds(delay_int),
+                  exponential_backoff_release_time_);
+}
+
+base::TimeTicks URLRequestThrottlerEntry::GetTimeNow() const {
+  return base::TimeTicks::Now();
+}
+
+void URLRequestThrottlerEntry::HandleCustomRetryAfter(
+    const std::string& header_value) {
+  // Input parameter is the number of seconds to wait in a floating point value.
+  double time_in_sec = 0;
+  bool conversion_is_ok = base::StringToDouble(header_value, &time_in_sec);
+
+  // Conversion of custom retry-after header value failed.
+  if (!conversion_is_ok)
+    return;
+
+  // We must use an int value later so we transform this in milliseconds.
+  int64 value_ms = static_cast<int64>(0.5 + time_in_sec * 1000);
+
+  if (maximum_backoff_ms_ < value_ms || value_ms < 0)
+    return;
+
+  exponential_backoff_release_time_ = std::max(
+      (GetTimeNow() + base::TimeDelta::FromMilliseconds(value_ms)),
+      exponential_backoff_release_time_);
+}
+
+}  // namespace net
diff --git a/net/url_request/url_request_throttler_entry.h b/net/url_request/url_request_throttler_entry.h
new file mode 100644
index 0000000..9b8955d
--- /dev/null
+++ b/net/url_request/url_request_throttler_entry.h
@@ -0,0 +1,157 @@
+// Copyright (c) 2010 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.
+
+#ifndef NET_URL_REQUEST_URL_REQUEST_THROTTLER_ENTRY_H_
+#define NET_URL_REQUEST_URL_REQUEST_THROTTLER_ENTRY_H_
+
+#include <queue>
+#include <string>
+
+#include "base/basictypes.h"
+#include "net/url_request/url_request_throttler_entry_interface.h"
+
+namespace net {
+
+// URLRequestThrottlerEntry represents an entry of URLRequestThrottlerManager.
+// It analyzes requests of a specific URL over some period of time, in order to
+// deduce the back-off time for every request.
+// The back-off algorithm consists of two parts. Firstly, exponential back-off
+// is used when receiving 5XX server errors or malformed response bodies.
+// The exponential back-off rule is enforced by URLRequestHttpJob. Any request
+// sent during the back-off period will be cancelled.
+// Secondly, a sliding window is used to count recent requests to a given
+// destination and provide guidance (to the application level only) on whether
+// too many requests have been sent and when a good time to send the next one
+// would be. This is never used to deny requests at the network level.
+class URLRequestThrottlerEntry : public URLRequestThrottlerEntryInterface {
+ public:
+  // Sliding window period.
+  static const int kDefaultSlidingWindowPeriodMs;
+
+  // Maximum number of requests allowed in sliding window period.
+  static const int kDefaultMaxSendThreshold;
+
+  // Initial delay for exponential back-off.
+  static const int kDefaultInitialBackoffMs;
+
+  // Additional constant to adjust back-off.
+  static const int kDefaultAdditionalConstantMs;
+
+  // Factor by which the waiting time will be multiplied.
+  static const double kDefaultMultiplyFactor;
+
+  // Fuzzing percentage. ex: 10% will spread requests randomly
+  // between 90%-100% of the calculated time.
+  static const double kDefaultJitterFactor;
+
+  // Maximum amount of time we are willing to delay our request.
+  static const int kDefaultMaximumBackoffMs;
+
+  // Time after which the entry is considered outdated.
+  static const int kDefaultEntryLifetimeMs;
+
+  // Name of the header that servers can use to ask clients to delay their next
+  // request.
+  static const char kRetryHeaderName[];
+
+  URLRequestThrottlerEntry();
+
+  // The life span of instances created with this constructor is set to
+  // infinite.
+  // It is only used by unit tests.
+  URLRequestThrottlerEntry(int sliding_window_period_ms,
+                           int max_send_threshold,
+                           int initial_backoff_ms,
+                           int additional_constant_ms,
+                           double multiply_factor,
+                           double jitter_factor,
+                           int maximum_backoff_ms);
+
+  // Implementation of URLRequestThrottlerEntryInterface.
+  virtual bool IsDuringExponentialBackoff() const;
+  virtual int64 ReserveSendingTimeForNextRequest(
+      const base::TimeTicks& earliest_time);
+  virtual base::TimeTicks GetExponentialBackoffReleaseTime() const;
+  virtual void UpdateWithResponse(
+      const URLRequestThrottlerHeaderInterface* response);
+  virtual void ReceivedContentWasMalformed();
+
+  // Used by the manager, returns true if the entry needs to be garbage
+  // collected.
+  bool IsEntryOutdated() const;
+
+ protected:
+  virtual ~URLRequestThrottlerEntry();
+
+  void Initialize();
+
+  // Calculates the release time for exponential back-off.
+  base::TimeTicks CalculateExponentialBackoffReleaseTime();
+
+  // Equivalent to TimeTicks::Now(), virtual to be mockable for testing purpose.
+  virtual base::TimeTicks GetTimeNow() const;
+
+  // Used internally to increase release time following a retry-after header.
+  void HandleCustomRetryAfter(const std::string& header_value);
+
+  // Used by tests.
+  void set_exponential_backoff_release_time(
+      const base::TimeTicks& release_time) {
+    exponential_backoff_release_time_ = release_time;
+  }
+
+  // Used by tests.
+  base::TimeTicks sliding_window_release_time() const {
+    return sliding_window_release_time_;
+  }
+
+  // Used by tests.
+  void set_sliding_window_release_time(const base::TimeTicks& release_time) {
+    sliding_window_release_time_ = release_time;
+  }
+
+  // Used by tests.
+  void set_failure_count(int failure_count) {
+    failure_count_ = failure_count;
+  }
+
+ private:
+  // Timestamp calculated by the exponential back-off algorithm at which we are
+  // allowed to start sending requests again.
+  base::TimeTicks exponential_backoff_release_time_;
+
+  // Number of times we encounter server errors or malformed response bodies.
+  int failure_count_;
+
+  // If true, the last request response was a failure.
+  // Note that this member can be false at the same time as failure_count_ can
+  // be greater than 0, since we gradually decrease failure_count_, instead of
+  // resetting it to 0 directly, when we receive successful responses.
+  bool latest_response_was_failure_;
+
+  // Timestamp calculated by the sliding window algorithm for when we advise
+  // clients the next request should be made, at the earliest. Advisory only,
+  // not used to deny requests.
+  base::TimeTicks sliding_window_release_time_;
+
+  // A list of the recent send events. We use them to decide whether there are
+  // too many requests sent in sliding window.
+  std::queue<base::TimeTicks> send_log_;
+
+  const base::TimeDelta sliding_window_period_;
+  const int max_send_threshold_;
+  const int initial_backoff_ms_;
+  const int additional_constant_ms_;
+  const double multiply_factor_;
+  const double jitter_factor_;
+  const int maximum_backoff_ms_;
+  // Set to -1 if the entry never expires.
+  const int entry_lifetime_ms_;
+
+  DISALLOW_COPY_AND_ASSIGN(URLRequestThrottlerEntry);
+};
+
+}  // namespace net
+
+#endif  // NET_URL_REQUEST_URL_REQUEST_THROTTLER_ENTRY_H_
diff --git a/net/url_request/url_request_throttler_entry_interface.h b/net/url_request/url_request_throttler_entry_interface.h
new file mode 100644
index 0000000..616e1d0
--- /dev/null
+++ b/net/url_request/url_request_throttler_entry_interface.h
@@ -0,0 +1,63 @@
+// Copyright (c) 2010 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.
+
+#ifndef NET_URL_REQUEST_URL_REQUEST_THROTTLER_ENTRY_INTERFACE_H_
+#define NET_URL_REQUEST_URL_REQUEST_THROTTLER_ENTRY_INTERFACE_H_
+
+#include "base/basictypes.h"
+#include "base/ref_counted.h"
+#include "base/time.h"
+
+namespace net {
+
+class URLRequestThrottlerHeaderInterface;
+
+// Interface provided on entries of the URL request throttler manager.
+class URLRequestThrottlerEntryInterface
+    : public base::RefCounted<URLRequestThrottlerEntryInterface> {
+ public:
+  URLRequestThrottlerEntryInterface() {}
+
+  // Returns true when we have encountered server errors and are doing
+  // exponential back-off.
+  // URLRequestHttpJob checks this method prior to every request; it cancels
+  // requests if this method returns true.
+  virtual bool IsDuringExponentialBackoff() const = 0;
+
+  // Calculates a recommended sending time for the next request and reserves it.
+  // The sending time is not earlier than the current exponential back-off
+  // release time or |earliest_time|. Moreover, the previous results of
+  // the method are taken into account, in order to make sure they are spread
+  // properly over time.
+  // Returns the recommended delay before sending the next request, in
+  // milliseconds. The return value is always positive or 0.
+  // Although it is not mandatory, respecting the value returned by this method
+  // is helpful to avoid traffic overload.
+  virtual int64 ReserveSendingTimeForNextRequest(
+      const base::TimeTicks& earliest_time) = 0;
+
+  // Returns the time after which requests are allowed.
+  virtual base::TimeTicks GetExponentialBackoffReleaseTime() const = 0;
+
+  // This method needs to be called each time a response is received.
+  virtual void UpdateWithResponse(
+      const URLRequestThrottlerHeaderInterface* response) = 0;
+
+  // Lets higher-level modules, that know how to parse particular response
+  // bodies, notify of receiving malformed content for the given URL. This will
+  // be handled by the throttler as if an HTTP 5xx response had been received to
+  // the request, i.e. it will count as a failure.
+  virtual void ReceivedContentWasMalformed() = 0;
+
+ protected:
+  virtual ~URLRequestThrottlerEntryInterface() {}
+
+ private:
+  friend class base::RefCounted<URLRequestThrottlerEntryInterface>;
+  DISALLOW_COPY_AND_ASSIGN(URLRequestThrottlerEntryInterface);
+};
+
+}  // namespace net
+
+#endif  // NET_URL_REQUEST_URL_REQUEST_THROTTLER_ENTRY_INTERFACE_H_
diff --git a/net/url_request/url_request_throttler_header_adapter.cc b/net/url_request/url_request_throttler_header_adapter.cc
new file mode 100644
index 0000000..e453071c
--- /dev/null
+++ b/net/url_request/url_request_throttler_header_adapter.cc
@@ -0,0 +1,27 @@
+// Copyright (c) 2010 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 "net/url_request/url_request_throttler_header_adapter.h"
+
+#include "net/http/http_response_headers.h"
+
+namespace net {
+
+URLRequestThrottlerHeaderAdapter::URLRequestThrottlerHeaderAdapter(
+    net::HttpResponseHeaders* headers)
+    : response_header_(headers) {
+}
+
+std::string URLRequestThrottlerHeaderAdapter::GetNormalizedValue(
+    const std::string& key) const {
+  std::string return_value;
+  response_header_->GetNormalizedHeader(key, &return_value);
+  return return_value;
+}
+
+int URLRequestThrottlerHeaderAdapter::GetResponseCode() const {
+  return response_header_->response_code();
+}
+
+}  // namespace net
diff --git a/net/url_request/url_request_throttler_header_adapter.h b/net/url_request/url_request_throttler_header_adapter.h
new file mode 100644
index 0000000..599a9f6
--- /dev/null
+++ b/net/url_request/url_request_throttler_header_adapter.h
@@ -0,0 +1,34 @@
+// Copyright (c) 2010 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.
+
+#ifndef NET_URL_REQUEST_URL_REQUEST_THROTTLER_HEADER_ADAPTER_H_
+#define NET_URL_REQUEST_URL_REQUEST_THROTTLER_HEADER_ADAPTER_H_
+
+#include <string>
+
+#include "base/ref_counted.h"
+#include "net/url_request/url_request_throttler_header_interface.h"
+
+namespace net {
+
+class HttpResponseHeaders;
+
+// Adapter for the HTTP header interface of the URL request throttler component.
+class URLRequestThrottlerHeaderAdapter
+    : public URLRequestThrottlerHeaderInterface {
+ public:
+  explicit URLRequestThrottlerHeaderAdapter(net::HttpResponseHeaders* headers);
+  virtual ~URLRequestThrottlerHeaderAdapter() {}
+
+  // Implementation of URLRequestThrottlerHeaderInterface
+  virtual std::string GetNormalizedValue(const std::string& key) const;
+  virtual int GetResponseCode() const;
+
+ private:
+  const scoped_refptr<net::HttpResponseHeaders> response_header_;
+};
+
+}  // namespace net
+
+#endif  // NET_URL_REQUEST_URL_REQUEST_THROTTLER_HEADER_ADAPTER_H_
diff --git a/net/url_request/url_request_throttler_header_interface.h b/net/url_request/url_request_throttler_header_interface.h
new file mode 100644
index 0000000..c69d185
--- /dev/null
+++ b/net/url_request/url_request_throttler_header_interface.h
@@ -0,0 +1,28 @@
+// Copyright (c) 2010 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.
+
+#ifndef NET_URL_REQUEST_URL_REQUEST_THROTTLER_HEADER_INTERFACE_H_
+#define NET_URL_REQUEST_URL_REQUEST_THROTTLER_HEADER_INTERFACE_H_
+
+#include <string>
+
+namespace net {
+
+// Interface to an HTTP header to enforce we have the methods we need.
+class URLRequestThrottlerHeaderInterface {
+ public:
+  virtual ~URLRequestThrottlerHeaderInterface() {}
+
+  // Method that enables us to fetch the header value by its key.
+  // ex: location: www.example.com -> key = "location" value = "www.example.com"
+  // If the key does not exist, it returns an empty string.
+  virtual std::string GetNormalizedValue(const std::string& key) const = 0;
+
+  // Returns the HTTP response code associated with the request.
+  virtual int GetResponseCode() const = 0;
+};
+
+}  // namespace net
+
+#endif  // NET_URL_REQUEST_URL_REQUEST_THROTTLER_HEADER_INTERFACE_H_
diff --git a/net/url_request/url_request_throttler_manager.cc b/net/url_request/url_request_throttler_manager.cc
new file mode 100644
index 0000000..5428d9a
--- /dev/null
+++ b/net/url_request/url_request_throttler_manager.cc
@@ -0,0 +1,107 @@
+// Copyright (c) 2010 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 "net/url_request/url_request_throttler_manager.h"
+
+#include "base/string_util.h"
+
+namespace net {
+
+const unsigned int URLRequestThrottlerManager::kMaximumNumberOfEntries = 1500;
+const unsigned int URLRequestThrottlerManager::kRequestsBetweenCollecting = 200;
+
+URLRequestThrottlerManager* URLRequestThrottlerManager::GetInstance() {
+  return Singleton<URLRequestThrottlerManager>::get();
+}
+
+scoped_refptr<URLRequestThrottlerEntryInterface>
+    URLRequestThrottlerManager::RegisterRequestUrl(const GURL &url) {
+  // Normalize the url.
+  std::string url_id = GetIdFromUrl(url);
+
+  // Periodically garbage collect old entries.
+  GarbageCollectEntriesIfNecessary();
+
+  // Find the entry in the map or create it.
+  scoped_refptr<URLRequestThrottlerEntry>& entry = url_entries_[url_id];
+  if (entry == NULL)
+    entry = new URLRequestThrottlerEntry();
+
+  return entry;
+}
+
+URLRequestThrottlerManager::URLRequestThrottlerManager()
+    : requests_since_last_gc_(0) {
+}
+
+URLRequestThrottlerManager::~URLRequestThrottlerManager() {
+  // Delete all entries.
+  url_entries_.clear();
+}
+
+std::string URLRequestThrottlerManager::GetIdFromUrl(const GURL& url) const {
+  if (!url.is_valid())
+    return url.possibly_invalid_spec();
+
+  if (url_id_replacements_ == NULL) {
+    url_id_replacements_.reset(new GURL::Replacements());
+
+    url_id_replacements_->ClearPassword();
+    url_id_replacements_->ClearUsername();
+    url_id_replacements_->ClearQuery();
+    url_id_replacements_->ClearRef();
+  }
+
+  GURL id = url.ReplaceComponents(*url_id_replacements_);
+  return StringToLowerASCII(id.spec());
+}
+
+void URLRequestThrottlerManager::GarbageCollectEntries() {
+  UrlEntryMap::iterator i = url_entries_.begin();
+
+  while (i != url_entries_.end()) {
+    if ((i->second)->IsEntryOutdated()) {
+      url_entries_.erase(i++);
+    } else {
+      ++i;
+    }
+  }
+
+  // In case something broke we want to make sure not to grow indefinitely.
+  while (url_entries_.size() > kMaximumNumberOfEntries) {
+    url_entries_.erase(url_entries_.begin());
+  }
+}
+
+void URLRequestThrottlerManager::GarbageCollectEntriesIfNecessary() {
+  requests_since_last_gc_++;
+  if (requests_since_last_gc_ < kRequestsBetweenCollecting)
+    return;
+
+  requests_since_last_gc_ = 0;
+  GarbageCollectEntries();
+}
+
+void URLRequestThrottlerManager::OverrideEntryForTests(
+    const GURL& url,
+    URLRequestThrottlerEntry* entry) {
+  if (entry == NULL)
+    return;
+
+  // Normalize the url.
+  std::string url_id = GetIdFromUrl(url);
+
+  // Periodically garbage collect old entries.
+  GarbageCollectEntriesIfNecessary();
+
+  url_entries_[url_id] = entry;
+}
+
+void URLRequestThrottlerManager::EraseEntryForTests(const GURL& url) {
+  // Normalize the url.
+  std::string url_id = GetIdFromUrl(url);
+  url_entries_.erase(url_id);
+}
+
+}  // namespace net
diff --git a/net/url_request/url_request_throttler_manager.h b/net/url_request/url_request_throttler_manager.h
new file mode 100644
index 0000000..6c8cd2f
--- /dev/null
+++ b/net/url_request/url_request_throttler_manager.h
@@ -0,0 +1,101 @@
+// Copyright (c) 2010 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.
+
+#ifndef NET_URL_REQUEST_URL_REQUEST_THROTTLER_MANAGER_H_
+#define NET_URL_REQUEST_URL_REQUEST_THROTTLER_MANAGER_H_
+
+#include <map>
+#include <string>
+
+#include "base/basictypes.h"
+#include "base/scoped_ptr.h"
+#include "base/singleton.h"
+#include "googleurl/src/gurl.h"
+#include "net/url_request/url_request_throttler_entry.h"
+
+namespace net {
+
+// Class that registers URL request throttler entries for URLs being accessed in
+// order to supervise traffic. URL requests for HTTP contents should register
+// their URLs in this manager on each request.
+// URLRequestThrottlerManager maintains a map of URL IDs to URL request
+// throttler entries. It creates URL request throttler entries when new URLs are
+// registered, and does garbage collection from time to time in order to clean
+// out outdated entries. URL ID consists of lowercased scheme, host, port and
+// path. All URLs converted to the same ID will share the same entry.
+//
+// NOTE: All usage of the singleton object of this class should be on the same
+// thread.
+class URLRequestThrottlerManager {
+ public:
+  static URLRequestThrottlerManager* GetInstance();
+
+  // Must be called for every request, returns the URL request throttler entry
+  // associated with the URL. The caller must inform this entry of some events.
+  // Please refer to url_request_throttler_entry_interface.h for further
+  // informations.
+  scoped_refptr<URLRequestThrottlerEntryInterface> RegisterRequestUrl(
+      const GURL& url);
+
+  // Registers a new entry in this service and overrides the existing entry (if
+  // any) for the URL. The service will hold a reference to the entry.
+  // It is only used by unit tests.
+  void OverrideEntryForTests(const GURL& url, URLRequestThrottlerEntry* entry);
+
+  // Explicitly erases an entry.
+  // This is useful to remove those entries which have got infinite lifetime and
+  // thus won't be garbage collected.
+  // It is only used by unit tests.
+  void EraseEntryForTests(const GURL& url);
+
+ protected:
+  URLRequestThrottlerManager();
+  ~URLRequestThrottlerManager();
+
+  // Method that allows us to transform a URL into an ID that can be used in our
+  // map. Resulting IDs will be lowercase and consist of the scheme, host, port
+  // and path (without query string, fragment, etc.).
+  // If the URL is invalid, the invalid spec will be returned, without any
+  // transformation.
+  std::string GetIdFromUrl(const GURL& url) const;
+
+  // Method that ensures the map gets cleaned from time to time. The period at
+  // which garbage collecting happens is adjustable with the
+  // kRequestBetweenCollecting constant.
+  void GarbageCollectEntriesIfNecessary();
+  // Method that does the actual work of garbage collecting.
+  void GarbageCollectEntries();
+
+  // Used by tests.
+  int GetNumberOfEntriesForTests() const { return url_entries_.size(); }
+
+ private:
+  friend struct DefaultSingletonTraits<URLRequestThrottlerManager>;
+
+  // From each URL we generate an ID composed of the scheme, host, port and path
+  // that allows us to uniquely map an entry to it.
+  typedef std::map<std::string, scoped_refptr<URLRequestThrottlerEntry> >
+      UrlEntryMap;
+
+  // Maximum number of entries that we are willing to collect in our map.
+  static const unsigned int kMaximumNumberOfEntries;
+  // Number of requests that will be made between garbage collection.
+  static const unsigned int kRequestsBetweenCollecting;
+
+  // Map that contains a list of URL ID and their matching
+  // URLRequestThrottlerEntry.
+  UrlEntryMap url_entries_;
+
+  // This keeps track of how many requests have been made. Used with
+  // GarbageCollectEntries.
+  unsigned int requests_since_last_gc_;
+
+  mutable scoped_ptr<GURL::Replacements> url_id_replacements_;
+
+  DISALLOW_COPY_AND_ASSIGN(URLRequestThrottlerManager);
+};
+
+}  // namespace net
+
+#endif  // NET_URL_REQUEST_URL_REQUEST_THROTTLER_MANAGER_H_
diff --git a/net/url_request/url_request_throttler_unittest.cc b/net/url_request/url_request_throttler_unittest.cc
new file mode 100644
index 0000000..0683f91
--- /dev/null
+++ b/net/url_request/url_request_throttler_unittest.cc
@@ -0,0 +1,346 @@
+// Copyright (c) 2010 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 "base/pickle.h"
+#include "base/scoped_ptr.h"
+#include "base/string_number_conversions.h"
+#include "base/time.h"
+#include "net/base/test_completion_callback.h"
+#include "net/url_request/url_request_context.h"
+#include "net/url_request/url_request_throttler_header_interface.h"
+#include "net/url_request/url_request_throttler_manager.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+using base::TimeDelta;
+using base::TimeTicks;
+
+namespace {
+class MockURLRequestThrottlerManager;
+
+class MockURLRequestThrottlerEntry : public net::URLRequestThrottlerEntry {
+ public :
+  MockURLRequestThrottlerEntry() {}
+  MockURLRequestThrottlerEntry(
+      const TimeTicks& exponential_backoff_release_time,
+      const TimeTicks& sliding_window_release_time,
+      const TimeTicks& fake_now)
+      : fake_time_now_(fake_now) {
+    set_exponential_backoff_release_time(exponential_backoff_release_time);
+    set_sliding_window_release_time(sliding_window_release_time);
+  }
+  virtual ~MockURLRequestThrottlerEntry() {}
+
+  void ResetToBlank(const TimeTicks& time_now) {
+    fake_time_now_ = time_now;
+    set_exponential_backoff_release_time(time_now);
+    set_failure_count(0);
+    set_sliding_window_release_time(time_now);
+  }
+
+  // Overridden for tests.
+  virtual TimeTicks GetTimeNow() const { return fake_time_now_; }
+
+  void set_exponential_backoff_release_time(
+      const base::TimeTicks& release_time) {
+    net::URLRequestThrottlerEntry::set_exponential_backoff_release_time(
+        release_time);
+  }
+
+  base::TimeTicks sliding_window_release_time() const {
+    return net::URLRequestThrottlerEntry::sliding_window_release_time();
+  }
+
+  void set_sliding_window_release_time(
+      const base::TimeTicks& release_time) {
+    net::URLRequestThrottlerEntry::set_sliding_window_release_time(
+        release_time);
+  }
+
+  TimeTicks fake_time_now_;
+};
+
+class MockURLRequestThrottlerHeaderAdapter
+    : public net::URLRequestThrottlerHeaderInterface {
+ public:
+  MockURLRequestThrottlerHeaderAdapter()
+      : fake_retry_value_("0.0"),
+        fake_response_code_(0) {
+  }
+
+  MockURLRequestThrottlerHeaderAdapter(const std::string& retry_value,
+                                       int response_code)
+      : fake_retry_value_(retry_value),
+        fake_response_code_(response_code) {
+  }
+
+  virtual ~MockURLRequestThrottlerHeaderAdapter() {}
+
+  virtual std::string GetNormalizedValue(const std::string& key) const {
+    if (key == MockURLRequestThrottlerEntry::kRetryHeaderName)
+      return fake_retry_value_;
+    return "";
+  }
+
+  virtual int GetResponseCode() const { return fake_response_code_; }
+
+  std::string fake_retry_value_;
+  int fake_response_code_;
+};
+
+class MockURLRequestThrottlerManager : public net::URLRequestThrottlerManager {
+ public:
+  MockURLRequestThrottlerManager() : create_entry_index_(0) {}
+
+  // Method to process the URL using URLRequestThrottlerManager protected
+  // method.
+  std::string DoGetUrlIdFromUrl(const GURL& url) { return GetIdFromUrl(url); }
+
+  // Method to use the garbage collecting method of URLRequestThrottlerManager.
+  void DoGarbageCollectEntries() { GarbageCollectEntries(); }
+
+  // Returns the number of entries in the map.
+  int GetNumberOfEntries() const { return GetNumberOfEntriesForTests(); }
+
+  void CreateEntry(bool is_outdated) {
+    TimeTicks time = TimeTicks::Now();
+    if (is_outdated) {
+      time -= TimeDelta::FromMilliseconds(
+          MockURLRequestThrottlerEntry::kDefaultEntryLifetimeMs + 1000);
+    }
+    std::string fake_url_string("http://www.fakeurl.com/");
+    fake_url_string.append(base::IntToString(create_entry_index_++));
+    GURL fake_url(fake_url_string);
+    OverrideEntryForTests(
+        fake_url,
+        new MockURLRequestThrottlerEntry(time, TimeTicks::Now(),
+                                         TimeTicks::Now()));
+  }
+
+ private:
+  int create_entry_index_;
+};
+
+struct TimeAndBool {
+  TimeAndBool(const TimeTicks& time_value, bool expected, int line_num) {
+    time = time_value;
+    result = expected;
+    line = line_num;
+  }
+  TimeTicks time;
+  bool result;
+  int line;
+};
+
+struct GurlAndString {
+  GurlAndString(const GURL& url_value,
+                const std::string& expected,
+                int line_num) {
+    url = url_value;
+    result = expected;
+    line = line_num;
+  }
+  GURL url;
+  std::string result;
+  int line;
+};
+
+}  // namespace
+
+class URLRequestThrottlerEntryTest : public testing::Test {
+ protected:
+  virtual void SetUp();
+  TimeTicks now_;
+  scoped_refptr<MockURLRequestThrottlerEntry> entry_;
+};
+
+void URLRequestThrottlerEntryTest::SetUp() {
+  now_ = TimeTicks::Now();
+  entry_ = new MockURLRequestThrottlerEntry();
+  entry_->ResetToBlank(now_);
+}
+
+std::ostream& operator<<(std::ostream& out, const base::TimeTicks& time) {
+  return out << time.ToInternalValue();
+}
+
+TEST_F(URLRequestThrottlerEntryTest, InterfaceDuringExponentialBackoff) {
+  entry_->set_exponential_backoff_release_time(
+      entry_->fake_time_now_ + TimeDelta::FromMilliseconds(1));
+  EXPECT_TRUE(entry_->IsDuringExponentialBackoff());
+}
+
+TEST_F(URLRequestThrottlerEntryTest, InterfaceNotDuringExponentialBackoff) {
+  entry_->set_exponential_backoff_release_time(entry_->fake_time_now_);
+  EXPECT_FALSE(entry_->IsDuringExponentialBackoff());
+  entry_->set_exponential_backoff_release_time(
+      entry_->fake_time_now_ - TimeDelta::FromMilliseconds(1));
+  EXPECT_FALSE(entry_->IsDuringExponentialBackoff());
+}
+
+TEST_F(URLRequestThrottlerEntryTest, InterfaceUpdateRetryAfter) {
+  // If the response we received has a retry-after field,
+  // the request should be delayed.
+  MockURLRequestThrottlerHeaderAdapter header_w_delay_header("5.5", 200);
+  entry_->UpdateWithResponse(&header_w_delay_header);
+  EXPECT_GT(entry_->GetExponentialBackoffReleaseTime(), entry_->fake_time_now_)
+      << "When the server put a positive value in retry-after we should "
+         "increase release_time";
+
+  entry_->ResetToBlank(now_);
+  header_w_delay_header.fake_retry_value_ = "-5.5";
+  EXPECT_EQ(entry_->GetExponentialBackoffReleaseTime(), entry_->fake_time_now_)
+      << "When given a negative value, it should not change the release_time";
+}
+
+TEST_F(URLRequestThrottlerEntryTest, InterfaceUpdateFailure) {
+  MockURLRequestThrottlerHeaderAdapter failure_response("0", 505);
+  entry_->UpdateWithResponse(&failure_response);
+  EXPECT_GT(entry_->GetExponentialBackoffReleaseTime(), entry_->fake_time_now_)
+      << "A failure should increase the release_time";
+}
+
+TEST_F(URLRequestThrottlerEntryTest, InterfaceUpdateSuccess) {
+  MockURLRequestThrottlerHeaderAdapter success_response("0", 200);
+  entry_->UpdateWithResponse(&success_response);
+  EXPECT_EQ(entry_->GetExponentialBackoffReleaseTime(), entry_->fake_time_now_)
+      << "A success should not add any delay";
+}
+
+TEST_F(URLRequestThrottlerEntryTest, InterfaceUpdateSuccessThenFailure) {
+  MockURLRequestThrottlerHeaderAdapter failure_response("0", 500);
+  MockURLRequestThrottlerHeaderAdapter success_response("0", 200);
+  entry_->UpdateWithResponse(&success_response);
+  entry_->UpdateWithResponse(&failure_response);
+  EXPECT_GT(entry_->GetExponentialBackoffReleaseTime(), entry_->fake_time_now_)
+      << "This scenario should add delay";
+}
+
+TEST_F(URLRequestThrottlerEntryTest, IsEntryReallyOutdated) {
+  TimeDelta lifetime = TimeDelta::FromMilliseconds(
+      MockURLRequestThrottlerEntry::kDefaultEntryLifetimeMs);
+  const TimeDelta kFiveMs = TimeDelta::FromMilliseconds(5);
+
+  TimeAndBool test_values[] = {
+      TimeAndBool(now_, false, __LINE__),
+      TimeAndBool(now_ - kFiveMs, false, __LINE__),
+      TimeAndBool(now_ + kFiveMs, false, __LINE__),
+      TimeAndBool(now_ - lifetime, false, __LINE__),
+      TimeAndBool(now_ - (lifetime + kFiveMs), true, __LINE__)};
+
+  for (unsigned int i = 0; i < arraysize(test_values); ++i) {
+    entry_->set_exponential_backoff_release_time(test_values[i].time);
+    EXPECT_EQ(entry_->IsEntryOutdated(), test_values[i].result) <<
+        "Test case #" << i << " line " << test_values[i].line << " failed";
+  }
+}
+
+TEST_F(URLRequestThrottlerEntryTest, MaxAllowedBackoff) {
+  for (int i = 0; i < 30; ++i) {
+    MockURLRequestThrottlerHeaderAdapter response_adapter("0.0", 505);
+    entry_->UpdateWithResponse(&response_adapter);
+  }
+
+  TimeDelta delay = entry_->GetExponentialBackoffReleaseTime() - now_;
+  EXPECT_EQ(delay.InMilliseconds(),
+            MockURLRequestThrottlerEntry::kDefaultMaximumBackoffMs);
+}
+
+TEST_F(URLRequestThrottlerEntryTest, MalformedContent) {
+  MockURLRequestThrottlerHeaderAdapter response_adapter("0.0", 505);
+  for (int i = 0; i < 5; ++i)
+    entry_->UpdateWithResponse(&response_adapter);
+
+  TimeTicks release_after_failures = entry_->GetExponentialBackoffReleaseTime();
+
+  // Inform the entry that a response body was malformed, which is supposed to
+  // increase the back-off time.
+  entry_->ReceivedContentWasMalformed();
+  EXPECT_GT(entry_->GetExponentialBackoffReleaseTime(), release_after_failures);
+}
+
+TEST_F(URLRequestThrottlerEntryTest, SlidingWindow) {
+  int max_send = net::URLRequestThrottlerEntry::kDefaultMaxSendThreshold;
+  int sliding_window =
+      net::URLRequestThrottlerEntry::kDefaultSlidingWindowPeriodMs;
+
+  TimeTicks time_1 = entry_->fake_time_now_ +
+      TimeDelta::FromMilliseconds(sliding_window / 3);
+  TimeTicks time_2 = entry_->fake_time_now_ +
+      TimeDelta::FromMilliseconds(2 * sliding_window / 3);
+  TimeTicks time_3 = entry_->fake_time_now_ +
+      TimeDelta::FromMilliseconds(sliding_window);
+  TimeTicks time_4 = entry_->fake_time_now_ +
+      TimeDelta::FromMilliseconds(sliding_window + 2 * sliding_window / 3);
+
+  entry_->set_exponential_backoff_release_time(time_1);
+
+  for (int i = 0; i < max_send / 2; ++i) {
+    EXPECT_EQ(2 * sliding_window / 3,
+              entry_->ReserveSendingTimeForNextRequest(time_2));
+  }
+  EXPECT_EQ(time_2, entry_->sliding_window_release_time());
+
+  entry_->fake_time_now_ = time_3;
+
+  for (int i = 0; i < (max_send + 1) / 2; ++i)
+    EXPECT_EQ(0, entry_->ReserveSendingTimeForNextRequest(TimeTicks()));
+
+  EXPECT_EQ(time_4, entry_->sliding_window_release_time());
+}
+
+TEST(URLRequestThrottlerManager, IsUrlStandardised) {
+  MockURLRequestThrottlerManager manager;
+  GurlAndString test_values[] = {
+      GurlAndString(GURL("http://www.example.com"),
+                    std::string("http://www.example.com/"), __LINE__),
+      GurlAndString(GURL("http://www.Example.com"),
+                    std::string("http://www.example.com/"), __LINE__),
+      GurlAndString(GURL("http://www.ex4mple.com/Pr4c71c41"),
+                    std::string("http://www.ex4mple.com/pr4c71c41"), __LINE__),
+      GurlAndString(GURL("http://www.example.com/0/token/false"),
+                    std::string("http://www.example.com/0/token/false"),
+                    __LINE__),
+      GurlAndString(GURL("http://www.example.com/index.php?code=javascript"),
+                    std::string("http://www.example.com/index.php"), __LINE__),
+      GurlAndString(GURL("http://www.example.com/index.php?code=1#superEntry"),
+                    std::string("http://www.example.com/index.php"),
+                    __LINE__),
+      GurlAndString(GURL("http://www.example.com:1234/"),
+                    std::string("http://www.example.com:1234/"), __LINE__)};
+
+  for (unsigned int i = 0; i < arraysize(test_values); ++i) {
+    std::string temp = manager.DoGetUrlIdFromUrl(test_values[i].url);
+    EXPECT_EQ(temp, test_values[i].result) <<
+        "Test case #" << i << " line " << test_values[i].line << " failed";
+  }
+}
+
+TEST(URLRequestThrottlerManager, AreEntriesBeingCollected) {
+  MockURLRequestThrottlerManager manager;
+
+  manager.CreateEntry(true);  // true = Entry is outdated.
+  manager.CreateEntry(true);
+  manager.CreateEntry(true);
+  manager.DoGarbageCollectEntries();
+  EXPECT_EQ(0, manager.GetNumberOfEntries());
+
+  manager.CreateEntry(false);
+  manager.CreateEntry(false);
+  manager.CreateEntry(false);
+  manager.CreateEntry(true);
+  manager.DoGarbageCollectEntries();
+  EXPECT_EQ(3, manager.GetNumberOfEntries());
+}
+
+TEST(URLRequestThrottlerManager, IsHostBeingRegistered) {
+  MockURLRequestThrottlerManager manager;
+
+  manager.RegisterRequestUrl(GURL("http://www.example.com/"));
+  manager.RegisterRequestUrl(GURL("http://www.google.com/"));
+  manager.RegisterRequestUrl(GURL("http://www.google.com/index/0"));
+  manager.RegisterRequestUrl(GURL("http://www.google.com/index/0?code=1"));
+  manager.RegisterRequestUrl(GURL("http://www.google.com/index/0#lolsaure"));
+
+  EXPECT_EQ(3, manager.GetNumberOfEntries());
+}