Don't restart the ImageQualityController timer unless it is already half over.

third_party/WebKit/Source/platform/Timer.h

Index: third_party/WebKit/Source/platform/Timer.h
diff --git a/third_party/WebKit/Source/platform/Timer.h b/third_party/WebKit/Source/platform/Timer.h
index 87e8aae279db9e5cabb782f2dcd5d1ea6d83035b..2724ce094364e29d052c4b5f15a9dc202d94dc71 100644
--- a/third_party/WebKit/Source/platform/Timer.h
+++ b/third_party/WebKit/Source/platform/Timer.h
@@ -54,7 +54,7 @@ public:
     {
         start(repeatInterval, repeatInterval, caller);
     }
-    void startOneShot(double interval, const WebTraceLocation& caller)
+    virtual void startOneShot(double interval, const WebTraceLocation& caller)
     {
         start(interval, 0, caller);
     }