Add an API to get total size of Drive cache including non-evictable ones.

components/drive/chromeos/file_cache.cc

Index: components/drive/chromeos/file_cache.cc
diff --git a/components/drive/chromeos/file_cache.cc b/components/drive/chromeos/file_cache.cc
index 37c0e87ff9e96ba26a55fcd178ce18cae960bb68..5b554b839797750afb8bde4647ef441ba73cf068 100644
--- a/components/drive/chromeos/file_cache.cc
+++ b/components/drive/chromeos/file_cache.cc
@@ -264,10 +264,31 @@ bool FileCache::FreeDiskSpaceIfNeededFor(int64_t num_bytes) {
   return GetAvailableSpace() >= num_bytes;
 }
 
-uint64_t FileCache::CalculateEvictableCacheSize() {
+int64_t FileCache::CalculateCacheSize() {
   AssertOnSequencedWorkerPool();
 
-  uint64_t evictable_cache_size = 0;
+  int64_t total_cache_size = 0;
+  int64_t cache_size = 0;
+
+  std::unique_ptr<ResourceMetadataStorage::Iterator> it =
+      storage_->GetIterator();
+  for (; !it->IsAtEnd(); it->Advance()) {
+    if (base::GetFileSize(GetCacheFilePath(it->GetID()), &cache_size)) {

[yawano, 2016/06/08 11:53:44]

We should check the existence of cache by checking metadata before getting file
size by base::GetFileSize to avoid unnecessary IO.

[fukino, 2016/06/09 04:36:47]

Nice catch! Done.

[yawano, 2016/06/09 05:19:19]

You also need to check is_present to know whether cache file presents or not. -
https://cs.chromium.org/chromium/src/out/Debug/gen/components/drive/drive.pb....

Also would it be better to check has_file_specific_info too since it's optional
field? -
https://cs.chromium.org/chromium/src/out/Debug/gen/components/drive/drive.pb....

[fukino, 2016/06/09 06:38:21]

Done.

+      DCHECK_GE(cache_size, 0);
+      total_cache_size += cache_size;
+    }
+  }
+
+  if (it->HasError())
+    return 0;
+
+  return total_cache_size;
+}
+
+int64_t FileCache::CalculateEvictableCacheSize() {
+  AssertOnSequencedWorkerPool();
+
+  int64_t evictable_cache_size = 0;
   int64_t cache_size = 0;
 
   std::unique_ptr<ResourceMetadataStorage::Iterator> it =