Add UMA stats for ExtensionCache

chrome/browser/extensions/updater/local_extension_cache.cc

Index: chrome/browser/extensions/updater/local_extension_cache.cc
diff --git a/chrome/browser/extensions/updater/local_extension_cache.cc b/chrome/browser/extensions/updater/local_extension_cache.cc
index 7411805ba65006239234ec5bac5faad35d37f2c2..b88e802bf054e73f1c3d33132ba5b2c48d12e23d 100644
--- a/chrome/browser/extensions/updater/local_extension_cache.cc
+++ b/chrome/browser/extensions/updater/local_extension_cache.cc
@@ -29,7 +29,7 @@ const char LocalExtensionCache::kCacheReadyFlagFileName[] = ".initialized";
 
 LocalExtensionCache::LocalExtensionCache(
     const base::FilePath& cache_dir,
-    size_t max_cache_size,
+    uint64 max_cache_size,
     const base::TimeDelta& max_cache_age,
     const scoped_refptr<base::SequencedTaskRunner>& backend_task_runner)
     : cache_dir_(cache_dir),
@@ -151,6 +151,21 @@ bool LocalExtensionCache::RemoveExtension(const std::string& id) {
   return true;
 }
 
+bool LocalExtensionCache::GetStatistics(uint64* cache_size,
+                                        size_t* extensions_count) {
+  if (state_ != kReady)
+    return false;
+
+  *cache_size = 0;
+  for (CacheMap::iterator it = cached_extensions_.begin();
+       it != cached_extensions_.end(); ++it) {
+    *cache_size += it->second.size;
+  }
+  *extensions_count = cached_extensions_.size();
+
+  return true;
+}
+
 void LocalExtensionCache::SetCacheStatusPollingDelayForTests(
     const base::TimeDelta& delay) {
   cache_status_polling_delay_ = delay;
@@ -425,7 +440,7 @@ void LocalExtensionCache::CleanUp() {
 
   std::vector<CacheMap::iterator> items;
   items.reserve(cached_extensions_.size());
-  size_t total_size = 0;
+  uint64_t total_size = 0;
   for (CacheMap::iterator it = cached_extensions_.begin();
        it != cached_extensions_.end(); ++it) {
     items.push_back(it);
@@ -447,7 +462,7 @@ void LocalExtensionCache::CleanUp() {
 LocalExtensionCache::CacheItemInfo::CacheItemInfo(
     const std::string& version,
     const base::Time& last_used,
-    const size_t size,
+    uint64 size,
     const base::FilePath& file_path)
     : version(version), last_used(last_used), size(size), file_path(file_path) {
 }