cc: Add image decode queue functionality to image manager.

cc/raster/task.h

Index: cc/raster/task.h
diff --git a/cc/raster/task.h b/cc/raster/task.h
index 2c406077c8be59f3195cf4d00ba571c5571dd294..01c16a02f45035787df56d3526ed389f8ca3932a 100644
--- a/cc/raster/task.h
+++ b/cc/raster/task.h
@@ -7,6 +7,7 @@
 
 #include <stdint.h>
 
+#include <string>
 #include <vector>
 
 #include "base/memory/ref_counted.h"
@@ -38,6 +39,7 @@ class Task;
 //    └─────────┘         ╚══════════╝
 class CC_EXPORT TaskState {
  public:
+  bool IsNew() const;
   bool IsScheduled() const;
   bool IsRunning() const;
   bool IsFinished() const;
@@ -53,6 +55,8 @@ class CC_EXPORT TaskState {
   void DidFinish();
   void DidCancel();
 
+  std::string ToString() const;
+
  private:
   friend class Task;