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

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

Index: third_party/WebKit/Source/core/html/canvas/CanvasAsyncBlobCreator.cpp
diff --git a/third_party/WebKit/Source/core/html/canvas/CanvasAsyncBlobCreator.cpp b/third_party/WebKit/Source/core/html/canvas/CanvasAsyncBlobCreator.cpp
index 86acd77dab2b4b29382b64ffd2ec6394a39acbbb..4e61747e58d129538ed3a73008dd29ed0d736481 100644
--- a/third_party/WebKit/Source/core/html/canvas/CanvasAsyncBlobCreator.cpp
+++ b/third_party/WebKit/Source/core/html/canvas/CanvasAsyncBlobCreator.cpp
@@ -17,6 +17,7 @@
 #include "public/platform/WebTraceLocation.h"
 #include "wtf/CurrentTime.h"
 #include "wtf/Functional.h"
+#include <iostream>
 
 namespace blink {
 
@@ -107,6 +108,7 @@ void CanvasAsyncBlobCreator::initiateJpegEncoding(const double& quality)
 
 void CanvasAsyncBlobCreator::scheduleInitiatePngEncoding()
 {
+    std::cout << "Begin! Posting idle task to initiate" << std::endl;
     Platform::current()->mainThread()->scheduler()->postIdleTask(BLINK_FROM_HERE, bind<double>(&CanvasAsyncBlobCreator::initiatePngEncoding, this));
 }
 
@@ -117,6 +119,7 @@ void CanvasAsyncBlobCreator::initiatePngEncoding(double deadlineSeconds)
         return;
     }
 
+    std::cout << "Idle task is starting " << std::endl; 
     ASSERT(m_idleTaskStatus == IdleTaskNotStarted);
     m_idleTaskStatus = IdleTaskStarted;
 
@@ -134,10 +137,14 @@ void CanvasAsyncBlobCreator::idleEncodeRowsPng(double deadlineSeconds)
         return;
     }
 
+    if (m_numRowsCompleted > 0 )
+        std::cout << "Idle task continued... " << std::flush;
+
     unsigned char* inputPixels = m_data->data() + m_pixelRowStride * m_numRowsCompleted;
     for (int y = m_numRowsCompleted; y < m_size.height(); ++y) {
         if (isDeadlineNearOrPassed(deadlineSeconds)) {
             m_numRowsCompleted = y;
+            std::cout << "Idle task paused at row " << m_numRowsCompleted << "..." << std::flush;
             Platform::current()->currentThread()->scheduler()->postIdleTask(BLINK_FROM_HERE, bind<double>(&CanvasAsyncBlobCreator::idleEncodeRowsPng, this));
             return;
         }
@@ -148,6 +155,8 @@ void CanvasAsyncBlobCreator::idleEncodeRowsPng(double deadlineSeconds)
     PNGImageEncoder::finalizePng(m_pngEncoderState.get());
 
     m_idleTaskStatus = IdleTaskCompleted;
+    std::cout << std::endl;
+    std::cout << "Idle task completed " << std::endl;
 
     if (isDeadlineNearOrPassed(deadlineSeconds)) {
         Platform::current()->mainThread()->getWebTaskRunner()->postTask(BLINK_FROM_HERE, bind(&CanvasAsyncBlobCreator::createBlobAndInvokeCallback, this));