Demonstration: postIdleTask does not work when users do not move mouse

third_party/WebKit/Source/core/html/canvas/CanvasAsyncBlobCreator.h

Index: third_party/WebKit/Source/core/html/canvas/CanvasAsyncBlobCreator.h
diff --git a/third_party/WebKit/Source/core/html/canvas/CanvasAsyncBlobCreator.h b/third_party/WebKit/Source/core/html/canvas/CanvasAsyncBlobCreator.h
index 3f038c276abdaa800e33b509a2acaadf6bb1604e..232a8fc7a941ccc68cc01474a9ac68ec62bef3c0 100644
--- a/third_party/WebKit/Source/core/html/canvas/CanvasAsyncBlobCreator.h
+++ b/third_party/WebKit/Source/core/html/canvas/CanvasAsyncBlobCreator.h
@@ -11,6 +11,7 @@
 #include "wtf/OwnPtr.h"
 #include "wtf/Vector.h"
 #include "wtf/text/WTFString.h"
+#include <iostream>
 
 namespace blink {
 
@@ -31,8 +32,8 @@ public:
         IdleTaskNotSupported // Idle tasks are not implemented for some image types
     };
     // Methods are virtual for mocking in unit tests
-    virtual void signalTaskSwitchInStartTimeoutEventForTesting() { }
-    virtual void signalTaskSwitchInCompleteTimeoutEventForTesting() { }
+    virtual void signalTaskSwitchInStartTimeoutEventForTesting() { std::cout << "Idle task starts too slow! Have to switch to non-idle task at StartTimeoutEvent" << std::endl; }
+    virtual void signalTaskSwitchInCompleteTimeoutEventForTesting() { std::cout << "Idle task paused for too long! Have to switch to non-idle task at CompleteTimeoutEvent" << std::endl; }
 
     DEFINE_INLINE_VIRTUAL_TRACE()
     {