Drive: add a method to clear all local cache.

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 7558f7c0bcdbb1539d64d31b40e63c4d67c9d58e..0327317cf5be649ac0f3cf75aadd6c5566f23911 100644
--- a/chrome/browser/chromeos/gdata/gdata_cache.cc
+++ b/chrome/browser/chromeos/gdata/gdata_cache.cc
@@ -240,8 +240,8 @@ void CollectAnyFile(std::vector<std::string>* resource_ids,
 // Runs callback with pointers dereferenced.
 // Used to implement SetMountedStateOnUIThread.
 void RunSetMountedStateCallback(const SetMountedStateCallback& callback,
-                                GDataFileError* error,
-                                FilePath* cache_file_path) {
+                                const GDataFileError* error,
+                                const FilePath* cache_file_path) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   DCHECK(error);
   DCHECK(cache_file_path);
@@ -683,6 +683,22 @@ void GDataCache::RemoveOnUIThread(const std::string& resource_id,
                  ""  /* md5 */));
 }
 
+void GDataCache::ClearAllOnUIThread(const SetMountedStateCallback& callback) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+
+  GDataFileError* error = new GDataFileError(GDATA_FILE_OK);
+
+  blocking_task_runner_->PostTaskAndReply(
+      FROM_HERE,
+      base::Bind(&GDataCache::ClearAll,
+                 base::Unretained(this),
+                 error),
+      base::Bind(&RunSetMountedStateCallback,
+                 callback,
+                 base::Owned(error),
+                 &cache_root_path_));
+}
+
 void GDataCache::RequestInitializeOnUIThread() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
@@ -1436,6 +1452,13 @@ void GDataCache::Remove(const std::string& resource_id,
   *error = GDATA_FILE_OK;
 }
 
+void GDataCache::ClearAll(GDataFileError* error) {
+  DCHECK(error);
+  file_util::Delete(cache_root_path_, true);
+  Initialize();
+  *error = GDATA_FILE_OK;
+}
+
 void GDataCache::OnPinned(GDataFileError* error,
                           const std::string& resource_id,
                           const std::string& md5,