[WIP] histroy: Adjust cache size OnMemoryStateChange()

components/history/core/browser/history_database.cc

Index: components/history/core/browser/history_database.cc
diff --git a/components/history/core/browser/history_database.cc b/components/history/core/browser/history_database.cc
index 260f0578f4dd3c88c251afa021cb29852df38efb..2a383b8b2579cf6096bb5756b9e7e22aafc681b2 100644
--- a/components/history/core/browser/history_database.cc
+++ b/components/history/core/browser/history_database.cc
@@ -40,6 +40,7 @@ const int kCurrentVersionNumber = 32;
 const int kCompatibleVersionNumber = 16;
 const char kEarlyExpirationThresholdKey[] = "early_expiration_threshold";
 const int kMaxHostsInMemory = 10000;
+const int kDefaultCacheSize = 1000;
 
 }  // namespace
 
@@ -66,7 +67,7 @@ sql::InitStatus HistoryDatabase::Init(const base::FilePath& history_name) {
   // value, tells us how much memory the cache will use maximum.
   // 1000 * 4kB = 4MB
   // TODO(brettw) scale this value to the amount of available memory.
-  db_.set_cache_size(1000);
+  db_.set_cache_size(kDefaultCacheSize);
 
   // Note that we don't set exclusive locking here. That's done by
   // BeginExclusiveMode below which is called later (we have to be in shared
@@ -295,6 +296,16 @@ void HistoryDatabase::TrimMemory(bool aggressively) {
   db_.TrimMemory(aggressively);
 }
 
+void HistoryDatabase::AdjustCacheMemory(memory_coordinator::MemoryState state) {
+  int cache_size = kDefaultCacheSize;
+  if (state == memory_coordinator::MemoryState::THROTTLED) {
+    cache_size = cache_size / 2;
+  } else if (state == memory_coordinator::MemoryState::SUSPENDED) {
+    cache_size = cache_size / 4;
+  }
+  db_.UpdateCacheSize(cache_size);
+}
+
 bool HistoryDatabase::Raze() {
   return db_.Raze();
 }