validation: Pass in chainstate to ::NotifyHeaderTip

[META] This commit should be followed up by removing the comments and
       assertions meant only to show that the change is correct.

Author: dongcarl

src/validation.cpp

@@ -2770,7 +2770,7 @@ static SynchronizationState GetSynchronizationState(bool init)
     return SynchronizationState::INIT_DOWNLOAD;
 }
 
-static bool NotifyHeaderTip() LOCKS_EXCLUDED(cs_main) {
+static bool NotifyHeaderTip(CChainState& chainstate) LOCKS_EXCLUDED(cs_main) {
     bool fNotify = false;
     bool fInitialBlockDownload = false;
     static CBlockIndex* pindexHeaderOld = nullptr;
@@ -2781,7 +2781,8 @@ static bool NotifyHeaderTip() LOCKS_EXCLUDED(cs_main) {
 
         if (pindexHeader != pindexHeaderOld) {
             fNotify = true;
-            fInitialBlockDownload = ::ChainstateActive().IsInitialBlockDownload();
+            assert(std::addressof(::ChainstateActive()) == std::addressof(chainstate));
+            fInitialBlockDownload = chainstate.IsInitialBlockDownload();
             pindexHeaderOld = pindexHeader;
         }
     }
@@ -3664,7 +3665,7 @@ bool ChainstateManager::ProcessNewBlockHeaders(const std::vector<CBlockHeader>&
             }
         }
     }
-    if (NotifyHeaderTip()) {
+    if (NotifyHeaderTip(::ChainstateActive())) {
         if (::ChainstateActive().IsInitialBlockDownload() && ppindex && *ppindex) {
             LogPrintf("Synchronizing blockheaders, height: %d (~%.2f%%)\n", (*ppindex)->nHeight, 100.0/((*ppindex)->nHeight+(GetAdjustedTime() - (*ppindex)->GetBlockTime()) / Params().GetConsensus().nPowTargetSpacing) * (*ppindex)->nHeight);
         }
@@ -3800,7 +3801,7 @@ bool ChainstateManager::ProcessNewBlock(const CChainParams& chainparams, const s
         }
     }
 
-    NotifyHeaderTip();
+    NotifyHeaderTip(::ChainstateActive());
 
     BlockValidationState state; // Only used to report errors, not invalidity - ignore it
     if (!::ChainstateActive().ActivateBestChain(state, chainparams, pblock))
@@ -4685,7 +4686,7 @@ void LoadExternalBlockFile(const CChainParams& chainparams, FILE* fileIn, FlatFi
                     }
                 }
 
-                NotifyHeaderTip();
+                NotifyHeaderTip(::ChainstateActive());
 
                 // Recursively process earlier encountered successors of this block
                 std::deque<uint256> queue;
@@ -4711,7 +4712,7 @@ void LoadExternalBlockFile(const CChainParams& chainparams, FILE* fileIn, FlatFi
                         }
                         range.first++;
                         mapBlocksUnknownParent.erase(it);
-                        NotifyHeaderTip();
+                        NotifyHeaderTip(::ChainstateActive());
                     }
                 }
             } catch (const std::exception& e) {