[CacheStorage] Temporarily preserve recently opened caches from CacheStorageDispatcherHost

content/browser/cache_storage/cache_storage_dispatcher_host.cc

Index: content/browser/cache_storage/cache_storage_dispatcher_host.cc
diff --git a/content/browser/cache_storage/cache_storage_dispatcher_host.cc b/content/browser/cache_storage/cache_storage_dispatcher_host.cc
index e3ab6fa7faf33cfdeeac9fc64716b046ba1e959a..b19a2887c90f9bdf9f0288920d643f42ad420601 100644
--- a/content/browser/cache_storage/cache_storage_dispatcher_host.cc
+++ b/content/browser/cache_storage/cache_storage_dispatcher_host.cc
@@ -10,8 +10,11 @@
 #include "base/bind.h"
 #include "base/logging.h"
 #include "base/macros.h"
+#include "base/stl_util.h"
 #include "base/strings/string16.h"
 #include "base/strings/utf_string_conversions.h"
+#include "base/threading/thread_task_runner_handle.h"
+#include "base/time/time.h"
 #include "base/trace_event/trace_event.h"
 #include "content/browser/bad_message.h"
 #include "content/browser/cache_storage/cache_storage_cache.h"
@@ -31,6 +34,7 @@ namespace content {
 namespace {
 
 const uint32_t kFilteredMessageClasses[] = {CacheStorageMsgStart};
+const int32_t kCachePreservationSeconds = 5;
 
 blink::WebServiceWorkerCacheError ToWebServiceWorkerCacheError(
     CacheStorageError err) {
@@ -63,8 +67,8 @@ bool OriginCanAccessCacheStorage(const url::Origin& origin) {
 
 CacheStorageDispatcherHost::CacheStorageDispatcherHost()
     : BrowserMessageFilter(kFilteredMessageClasses,
-                           arraysize(kFilteredMessageClasses)) {
-}
+                           arraysize(kFilteredMessageClasses)),
+      weak_ptr_factory_(this) {}
 
 CacheStorageDispatcherHost::~CacheStorageDispatcherHost() {
 }
@@ -354,6 +358,19 @@ void CacheStorageDispatcherHost::OnCacheStorageOpenCallback(
         thread_id, request_id, ToWebServiceWorkerCacheError(error)));
     return;
   }
+
+  // Hang on to the cache for a few seconds (if we aren't already doing so).
+  // This way if the user quickly closes and reopens it the next open operation
+  // will be fast.
+  if (!ContainsKey(preserved_cache_handles_, cache_handle->value())) {
+    preserved_cache_handles_[cache_handle->value()] = cache_handle->Clone();
+    base::ThreadTaskRunnerHandle::Get()->PostDelayedTask(
+        FROM_HERE,
+        base::Bind(&CacheStorageDispatcherHost::StopPreservingCache,
+                   weak_ptr_factory_.GetWeakPtr(), cache_handle->value()),
+        base::TimeDelta::FromSeconds(kCachePreservationSeconds));
+  }
+
   CacheID cache_id = StoreCacheReference(std::move(cache_handle));
   Send(new CacheStorageMsg_CacheStorageOpenSuccess(thread_id, request_id,
                                                    cache_id));
@@ -508,6 +525,12 @@ void CacheStorageDispatcherHost::OnCacheBatchCallback(
   Send(new CacheStorageMsg_CacheBatchSuccess(thread_id, request_id));
 }
 
+void CacheStorageDispatcherHost::StopPreservingCache(
+    const CacheStorageCache* cache) {
+  DCHECK(ContainsKey(preserved_cache_handles_, cache));
+  preserved_cache_handles_.erase(cache);
+}
+
 CacheStorageDispatcherHost::CacheID
 CacheStorageDispatcherHost::StoreCacheReference(
     std::unique_ptr<CacheStorageCacheHandle> cache_handle) {