Keep sync tasks alive as long as it's not finished

chrome/browser/chromeos/drive/sync_client.h

Index: chrome/browser/chromeos/drive/sync_client.h
diff --git a/chrome/browser/chromeos/drive/sync_client.h b/chrome/browser/chromeos/drive/sync_client.h
index a8f6d1b3a57ba8d7bec1b6afb0fd00e5375072e2..3aab63f02a8776f09aeb9cb2a8151b760b27bdc4 100644
--- a/chrome/browser/chromeos/drive/sync_client.h
+++ b/chrome/browser/chromeos/drive/sync_client.h
@@ -14,6 +14,7 @@
 #include "base/memory/weak_ptr.h"
 #include "base/time/time.h"
 #include "chrome/browser/chromeos/drive/file_errors.h"
+#include "chrome/browser/chromeos/drive/job_scheduler.h"
 #include "chrome/browser/chromeos/drive/resource_metadata.h"
 
 namespace base {
@@ -93,25 +94,38 @@ class SyncClient {
 
   // States of sync tasks.
   enum SyncState {
-    PENDING,
-    RUNNING,
+    SUSPENDED,  // Task is currently inactive.
+    PENDING,  // Task is going to run.
+    RUNNING,  // Task is running.
   };
 
+  typedef std::pair<SyncType, std::string> SyncTaskKey;
+
   struct SyncTask {
     SyncTask();
     ~SyncTask();
     SyncState state;
-    base::Callback<base::Closure()> task;
+    ClientContext context;
+    base::Callback<base::Closure(const ClientContext& context)> task;
     bool should_run_again;
     base::Closure cancel_closure;
+    std::vector<SyncTaskKey> dependent_tasks;
   };
 
-  typedef std::map<std::pair<SyncType, std::string>, SyncTask> SyncTasks;
+  typedef std::map<SyncTaskKey, SyncTask> SyncTasks;
+
+  // Performs a FETCH task.
+  base::Closure PerformFetchTask(const std::string& local_id,
+                                 const ClientContext& context);
 
   // Adds a FETCH task.
   void AddFetchTaskInternal(const std::string& local_id,
                             const base::TimeDelta& delay);
 
+  // Performs a UPDATE task.
+  base::Closure PerformUpdateTask(const std::string& local_id,
+                                  const ClientContext& context);
+
   // Adds a UPDATE task.
   void AddUpdateTaskInternal(const ClientContext& context,
                              const std::string& local_id,
@@ -132,8 +146,10 @@ class SyncClient {
   // Adds fetch tasks.
   void AddFetchTasks(const std::vector<std::string>* local_ids);
 
-  // Erases the task and returns true if task is completed.
-  bool OnTaskComplete(SyncType type, const std::string& local_id);
+  // Called when a task is completed.
+  void OnTaskComplete(SyncType type,
+                      const std::string& local_id,
+                      FileError error);
 
   // Called when the file for |local_id| is fetched.
   void OnFetchFileComplete(const std::string& local_id,
@@ -141,12 +157,11 @@ class SyncClient {
                            const base::FilePath& local_path,
                            scoped_ptr<ResourceEntry> entry);
 
-  // Called when the entry is updated.
-  void OnUpdateComplete(const std::string& local_id, FileError error);
-
-  // Adds update tasks for |entries|.
-  void AddChildUpdateTasks(const ResourceEntryVector* entries,
-                           FileError error);
+  // Adds the task as a dependent task of the parent entry's task.
+  void AddDependentTask(SyncType type,
+                        const std::string& local_id,
+                        const ResourceEntry* entry,
+                        FileError error);
 
   scoped_refptr<base::SequencedTaskRunner> blocking_task_runner_;
   file_system::OperationObserver* operation_observer_;