Replace the RepeatingTimer in ImageDecoder with a DelayTimer.

chrome/browser/image_decoder.h

Index: chrome/browser/image_decoder.h
diff --git a/chrome/browser/image_decoder.h b/chrome/browser/image_decoder.h
index ca7604350e97ea63b229a339666faa49bd1a6002..d3bd4e7cf638ab8285a448139f09ab37ff9eda21 100644
--- a/chrome/browser/image_decoder.h
+++ b/chrome/browser/image_decoder.h
@@ -141,11 +141,9 @@ class ImageDecoder : public content::UtilityProcessHostClient {
   // The UtilityProcessHost requests are sent to.
   base::WeakPtr<content::UtilityProcessHost> utility_process_host_;
 
-  // Calls StopBatchMode() after |kBatchModeTimeoutSeconds| have elapsed.
-  base::RepeatingTimer<ImageDecoder> batch_mode_timer_;
-
-  // The time Start() was last called.
-  base::TimeTicks last_request_;
+  // Calls StopBatchMode() after |kBatchModeTimeoutSeconds| have elapsed,
+  // unless a new decoding request resets the timer.
+  scoped_ptr<base::DelayTimer<ImageDecoder>> batch_mode_timer_;
 
   DISALLOW_COPY_AND_ASSIGN(ImageDecoder);
 };