Add coalescing timer to ResourceScheduler. CL 2 from BUG=128035.

content/browser/loader/resource_scheduler.h

Index: content/browser/loader/resource_scheduler.h
diff --git a/content/browser/loader/resource_scheduler.h b/content/browser/loader/resource_scheduler.h
index b445a6818fddec1e7726ff9b16c32ad5773d205d..4e4a81856d2a383a4fdbb615ec3b39157df1e7fa 100644
--- a/content/browser/loader/resource_scheduler.h
+++ b/content/browser/loader/resource_scheduler.h
@@ -12,6 +12,7 @@
 #include "base/compiler_specific.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/threading/non_thread_safe.h"
+#include "base/timer/timer.h"
 #include "content/common/content_export.h"
 #include "net/base/priority_queue.h"
 #include "net/base/request_priority.h"
@@ -69,6 +70,13 @@ class CONTENT_EXPORT ResourceScheduler : public base::NonThreadSafe {
   ResourceScheduler();
   ~ResourceScheduler();
 
+  // Use a mock timer when testing.
+  void set_timer_for_testing(scoped_ptr<base::Timer> timer) {
+    DCHECK(timer);

[mmenke, 2014/07/25 16:33:27]

Probably shouldn't have DCHECKs in header files.  It's a heavier weight from an
inlining perspective, and no one ever remembers to include logging.h, so you end
up either having include-what-you-use issues yourself, or encouraging other
files to have them.

+    coalescing_timer_.reset();
+    coalescing_timer_.reset(timer.release());

[mmenke, 2014/07/25 16:33:27]

Don't need two calls.

coalescing_timer_.reset(timer.release()); both deletes the old one and moves the
new one.

coalescing_timer_ = timer.Pass(); also works, not sure if one is preferred over
the other.

+  }
+
   // TODO(aiolos): Remove when throttling and coalescing have landed
   void SetThrottleOptionsForTesting(bool should_throttle, bool should_coalesce);
 
@@ -136,16 +144,26 @@ class CONTENT_EXPORT ResourceScheduler : public base::NonThreadSafe {
   // Called when a ScheduledResourceRequest is destroyed.
   void RemoveRequest(ScheduledResourceRequest* request);
 
-  // These Calls may update the ThrottleState of all clients, and have the
-  // potential to be re-entarant.
+  // These calls may update the ThrottleState of all clients, and have the
+  // potential to be re-entrant.
   // Called when a Client newly becomes active loading.
-  void DecrementActiveClientsLoading();
-  // Caled when a Client stops being active loading.
   void IncrementActiveClientsLoading();
+  // Called when an active and loading Client either completes loading or
+  // becomes inactive.
+  void DecrementActiveClientsLoading();
+
+  void OnLoadingActiveClientsStateChangedForAllClients();
+
+  size_t CountActiveClientsLoading() const;
+
+  // Called when a Client becomes coalesced.
+  void IncrementCoalescedClients();
+  // Called when a client stops being coalesced.
+  void DecrementCoalescedClients();
 
-  void OnLoadingActiveClientsStateChanged();
+  void LoadRequestsForAllCoalescedClients();
 
-  size_t CountActiveClientsLoading();
+  size_t CountCoalescedClients() const;
 
   // Update the queue position for |request|, possibly causing it to start
   // loading.
@@ -167,6 +185,9 @@ class CONTENT_EXPORT ResourceScheduler : public base::NonThreadSafe {
   bool should_throttle_;
   ClientMap client_map_;
   size_t active_clients_loading_;
+  size_t coalesced_clients_;
+  /* This is a repeating timer to initiate requests on COALESCED Clients. */

[mmenke, 2014/07/25 16:33:27]

nit:  Generally should use C++-style comments.

+  scoped_ptr<base::Timer> coalescing_timer_;
   RequestSet unowned_requests_;
 };