[DOMStorage] Rate limiting writes to disk.

content/browser/dom_storage/dom_storage_namespace.cc

 // Copyright 2013 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 "content/browser/dom_storage/dom_storage_namespace.h"
 
 #include "base/basictypes.h"
 #include "base/bind.h"
 #include "base/location.h"
 #include "base/logging.h"
@@ skipping 105 matching lines @@
   DOMStorageArea* area = OpenStorageArea(origin);
   area->FastClear();
   CloseStorageArea(area);
 }
 
 void DOMStorageNamespace::PurgeMemory(PurgeOption option) {
   if (directory_.empty())
     return;  // We can't purge w/o backing on disk.
   AreaMap::iterator it = areas_.begin();
   while (it != areas_.end()) {
-    // Leave it alone if changes are pending
-    if (it->second.area_->HasUncommittedChanges()) {
+    const AreaHolder& holder = it->second;
+
+    // We can't purge if there are changes pending.
+    if (holder.area_->HasUncommittedChanges()) {
+      if (holder.open_count_ == 0) {
+         // Schedule an immediate commit so the next time we're asked to purge,
+         // we can drop it from memory.
+         holder.area_->ScheduleImmediateCommit();
+      }
       ++it;
       continue;
     }
 
     // If not in use, we can shut it down and remove
     // it from our collection entirely.
-    if (it->second.open_count_ == 0) {
-      it->second.area_->Shutdown();
+    if (holder.open_count_ == 0) {
+      holder.area_->Shutdown();
       areas_.erase(it++);
       continue;
     }
 
     if (option == PURGE_AGGRESSIVE) {
       // If aggressive is true, we clear caches and such
       // for opened areas.
-      it->second.area_->PurgeMemory();
+      holder.area_->PurgeMemory();
     }
 
     ++it;
   }
 }
 
 void DOMStorageNamespace::Shutdown() {
   AreaMap::const_iterator it = areas_.begin();
   for (; it != areas_.end(); ++it)
     it->second.area_->Shutdown();
@@ skipping 24 matching lines @@
 
 DOMStorageNamespace::AreaHolder::AreaHolder(
     DOMStorageArea* area, int count)
     : area_(area), open_count_(count) {
 }
 
 DOMStorageNamespace::AreaHolder::~AreaHolder() {
 }
 
 }  // namespace content