Implement initialization for GDataCache to use in-memory metadata for tests.

chrome/browser/chromeos/gdata/gdata_cache.cc

Index: chrome/browser/chromeos/gdata/gdata_cache.cc
diff --git a/chrome/browser/chromeos/gdata/gdata_cache.cc b/chrome/browser/chromeos/gdata/gdata_cache.cc
index 6b2efb326d501475a755d3341c40fe6c673eae06..32af36bb8ddacf015e60d388db40fb46876b02c2 100644
--- a/chrome/browser/chromeos/gdata/gdata_cache.cc
+++ b/chrome/browser/chromeos/gdata/gdata_cache.cc
@@ -324,7 +324,8 @@ GDataCache::GDataCache(const FilePath& cache_root_path,
     : cache_root_path_(cache_root_path),
       cache_paths_(GetCachePaths(cache_root_path_)),
       blocking_task_runner_(blocking_task_runner),
-      weak_ptr_factory_(ALLOW_THIS_IN_INITIALIZER_LIST(this)) {
+      weak_ptr_factory_(ALLOW_THIS_IN_INITIALIZER_LIST(this)),
+      force_metadata_map_for_testing_(false) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 }
 
@@ -748,7 +749,7 @@ void GDataCache::Initialize() {
 
   InitCachePaths(cache_paths_);
   metadata_ = GDataCacheMetadata::CreateGDataCacheMetadata(
-      blocking_task_runner_).Pass();
+      blocking_task_runner_, force_metadata_map_for_testing_).Pass();
   metadata_->Initialize(cache_paths_);
 }
 
@@ -1524,6 +1525,10 @@ void GDataCache::GetCacheEntryHelper(const std::string& resource_id,
   *success = GetCacheEntry(resource_id, md5, cache_entry);
 }
 
+void GDataCache::ForceMetadataMapForTesting() {
+  force_metadata_map_for_testing_ = true;
+}
+
 // static
 FilePath GDataCache::GetCacheRootPath(Profile* profile) {
   FilePath cache_base_path;