Refactor how padding is calculated.

webrtc/call/bitrate_allocator.cc

Index: webrtc/call/bitrate_allocator.cc
diff --git a/webrtc/call/bitrate_allocator.cc b/webrtc/call/bitrate_allocator.cc
index 3672ef520ca3422bc372d2108b75abf9b5390666..efff2a50ed78e36aee8a1271df3d4fdc6e131146 100644
--- a/webrtc/call/bitrate_allocator.cc
+++ b/webrtc/call/bitrate_allocator.cc
@@ -24,17 +24,18 @@ namespace webrtc {
 const int kTransmissionMaxBitrateMultiplier = 2;
 const int kDefaultBitrateBps = 300000;
 
-BitrateAllocator::BitrateAllocator()
-    : bitrate_observer_configs_(),
+BitrateAllocator::BitrateAllocator(LimitObserver* limit_observer)
+    : limit_observer_(limit_observer),
+      bitrate_observer_configs_(),
       enforce_min_bitrate_(true),
       last_bitrate_bps_(kDefaultBitrateBps),
       last_non_zero_bitrate_bps_(kDefaultBitrateBps),
       last_fraction_loss_(0),
       last_rtt_(0) {}
 
-uint32_t BitrateAllocator::OnNetworkChanged(uint32_t bitrate,
-                                            uint8_t fraction_loss,
-                                            int64_t rtt) {
+void BitrateAllocator::OnNetworkChanged(uint32_t bitrate,
+                                        uint8_t fraction_loss,
+                                        int64_t rtt) {
   rtc::CritScope lock(&crit_sect_);
   last_bitrate_bps_ = bitrate;
   last_non_zero_bitrate_bps_ =
@@ -42,18 +43,16 @@ uint32_t BitrateAllocator::OnNetworkChanged(uint32_t bitrate,
   last_fraction_loss_ = fraction_loss;
   last_rtt_ = rtt;
 
-  uint32_t allocated_bitrate_bps = 0;
   ObserverAllocation allocation = AllocateBitrates(bitrate);
   for (const auto& kv : allocation) {
     kv.first->OnBitrateUpdated(kv.second, last_fraction_loss_, last_rtt_);
-    allocated_bitrate_bps += kv.second;
   }
-  return allocated_bitrate_bps;
 }
 
 int BitrateAllocator::AddObserver(BitrateAllocatorObserver* observer,
                                   uint32_t min_bitrate_bps,
                                   uint32_t max_bitrate_bps,
+                                  uint32_t pad_up_bitrate_bps,
                                   bool enforce_min_bitrate) {
   rtc::CritScope lock(&crit_sect_);
   // TODO(mflodman): Enforce this per observer.
@@ -70,10 +69,12 @@ int BitrateAllocator::AddObserver(BitrateAllocatorObserver* observer,
     // Update current configuration.
     it->min_bitrate_bps = min_bitrate_bps;
     it->max_bitrate_bps = max_bitrate_bps;
+    it->pad_up_bitrate_bps = pad_up_bitrate_bps;
   } else {
     // Add new settings.
-    bitrate_observer_configs_.push_back(ObserverConfig(
-        observer, min_bitrate_bps, max_bitrate_bps, enforce_min_bitrate));
+    bitrate_observer_configs_.push_back(
+        ObserverConfig(observer, min_bitrate_bps, max_bitrate_bps,
+                       pad_up_bitrate_bps, enforce_min_bitrate));
   }
 
   int new_observer_bitrate_bps = 0;
@@ -94,15 +95,49 @@ int BitrateAllocator::AddObserver(BitrateAllocatorObserver* observer,
     observer->OnBitrateUpdated(0, last_fraction_loss_, last_rtt_);
     new_observer_bitrate_bps = allocation[observer];
   }
+
+  UpdateAllocationLimits();
+
   return new_observer_bitrate_bps;
 }
 
+void BitrateAllocator::NotifyObserverInactive(
+    BitrateAllocatorObserver* observer,
+    bool inactive) {
+  rtc::CritScope lock(&crit_sect_);
+  auto iter = std::find_if(
+      bitrate_observer_configs_.begin(), bitrate_observer_configs_.end(),
+      [observer](const ObserverConfig& c) { return c.observer == observer; });
+  RTC_DCHECK(iter != bitrate_observer_configs_.end());
+  iter->active = !inactive;
+
+  UpdateAllocationLimits();
+}
+
+void BitrateAllocator::UpdateAllocationLimits() {
+  uint32_t total_requested_padding_bitrate = 0;
+  uint32_t total_requested_min_bitrate = 0;
+
+  for (const auto& config : bitrate_observer_configs_) {
+    if (enforce_min_bitrate_) {
+      total_requested_min_bitrate += config.min_bitrate_bps;
+    }
+    if (config.active)
+      total_requested_padding_bitrate += config.pad_up_bitrate_bps;
+  }
+  crit_sect_.Leave();
+  limit_observer_->OnAllocationLimitsChanged(total_requested_min_bitrate,
+                                             total_requested_padding_bitrate);
+  crit_sect_.Enter();
+}
+
 void BitrateAllocator::RemoveObserver(BitrateAllocatorObserver* observer) {
   rtc::CritScope lock(&crit_sect_);
   auto it = FindObserverConfig(observer);
   if (it != bitrate_observer_configs_.end()) {
     bitrate_observer_configs_.erase(it);
   }
+  UpdateAllocationLimits();
 }
 
 void BitrateAllocator::EnforceMinBitrate(bool enforce_min_bitrate) {