Simplify CanvasAsyncBlobCreator by removing ContextObserver and related tests

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 3f7d29e4ddd84be6e9303ae3406559741c5f3dad..cfcd5c7f6f7f65b4bf8ef185ac55b51f816fc1d2 100644
--- a/third_party/WebKit/Source/core/html/canvas/CanvasAsyncBlobCreator.cpp
+++ b/third_party/WebKit/Source/core/html/canvas/CanvasAsyncBlobCreator.cpp
@@ -4,7 +4,6 @@
 
 #include "CanvasAsyncBlobCreator.h"
 
-#include "core/dom/ContextLifecycleObserver.h"
 #include "core/fileapi/Blob.h"
 #include "platform/Task.h"
 #include "platform/ThreadSafeFunctional.h"
@@ -34,51 +33,14 @@ bool isDeadlineNearOrPassed(double deadlineSeconds)
 
 } // anonymous namespace
 
-class CanvasAsyncBlobCreator::ContextObserver final : public NoBaseWillBeGarbageCollected<CanvasAsyncBlobCreator::ContextObserver>, public ContextLifecycleObserver {
-    WILL_BE_USING_GARBAGE_COLLECTED_MIXIN(CanvasAsyncBlobCreator::ContextObserver);
-public:
-    ContextObserver(ExecutionContext* executionContext, CanvasAsyncBlobCreator* asyncBlobCreator)
-        : ContextLifecycleObserver(executionContext)
-        , m_asyncBlobCreator(asyncBlobCreator)
-    {
-    }
-
-    DECLARE_VIRTUAL_TRACE();
-
-    void contextDestroyed() override
-    {
-        ContextLifecycleObserver::contextDestroyed();
-        if (!!m_asyncBlobCreator) {
-            m_asyncBlobCreator->m_cancelled = true;
-            // After sending cancel signal to asyncBlobCreator, the observer has
-            // done its job and thus deref asyncBlobCreator for proper destruction
-            m_asyncBlobCreator = nullptr;
-        }
-    }
-
-    void dispose()
-    {
-        // In Oilpan context, on-heap ContextObserver sometimes live longer than
-        // off-heap CanvasAsyncBlobCreator, thus we need to dispose backref to
-        // m_asyncBlobCreator here when its destructor is called to avoid
-        // heap-use-after-free error.
-        m_asyncBlobCreator = nullptr;
-    }
-
-private:
-    CanvasAsyncBlobCreator* m_asyncBlobCreator;
-};
-
-PassRefPtr<CanvasAsyncBlobCreator> CanvasAsyncBlobCreator::create(PassRefPtr<DOMUint8ClampedArray> unpremultipliedRGBAImageData, const String& mimeType, const IntSize& size, BlobCallback* callback, ExecutionContext* executionContext)
+PassRefPtr<CanvasAsyncBlobCreator> CanvasAsyncBlobCreator::create(PassRefPtr<DOMUint8ClampedArray> unpremultipliedRGBAImageData, const String& mimeType, const IntSize& size, BlobCallback* callback)
 {
     RefPtr<CanvasAsyncBlobCreator> asyncBlobCreator = adoptRef(new CanvasAsyncBlobCreator(unpremultipliedRGBAImageData, mimeType, size, callback));
-    asyncBlobCreator->createContextObserver(executionContext);
     return asyncBlobCreator.release();
 }
 
 CanvasAsyncBlobCreator::CanvasAsyncBlobCreator(PassRefPtr<DOMUint8ClampedArray> data, const String& mimeType, const IntSize& size, BlobCallback* callback)
-    : m_cancelled(false)
-    , m_data(data)
+    : m_data(data)
     , m_size(size)
     , m_mimeType(mimeType)
     , m_callback(callback)
@@ -91,13 +53,6 @@ CanvasAsyncBlobCreator::CanvasAsyncBlobCreator(PassRefPtr<DOMUint8ClampedArray>
 
 CanvasAsyncBlobCreator::~CanvasAsyncBlobCreator()
 {
-    if (!!m_contextObserver)
-        m_contextObserver->dispose();
-}
-
-DEFINE_TRACE(CanvasAsyncBlobCreator::ContextObserver)
-{
-    ContextLifecycleObserver::trace(visitor);
 }
 
 void CanvasAsyncBlobCreator::scheduleAsyncBlobCreation(bool canUseIdlePeriodScheduling, double quality)
@@ -108,6 +63,9 @@ void CanvasAsyncBlobCreator::scheduleAsyncBlobCreation(bool canUseIdlePeriodSche
     // Make self-reference to keep this object alive until the final task completes
     m_selfRef = this;
 
+    // At the time being, progressive encoding is only applicable to png image format,
+    // and thus idle tasks scheduling can only be applied to png image format.
+    // TODO(xlai): Progressive encoding on jpeg and webp image formats (crbug.com/571398, crbug.com/571399)
     if (canUseIdlePeriodScheduling) {
         ASSERT(m_mimeType == "image/png");
         Platform::current()->mainThread()->scheduler()->postIdleTask(BLINK_FROM_HERE, WTF::bind<double>(&CanvasAsyncBlobCreator::initiatePngEncoding, this));
@@ -166,40 +124,7 @@ void CanvasAsyncBlobCreator::createBlobAndCall()
 void CanvasAsyncBlobCreator::encodeImageOnEncoderThread(double quality)
 {
     ASSERT(!isMainThread());
-    if (initializeEncodeImageOnEncoderThread()) {
-        if (m_mimeType == "image/png") {
-            // At the time being, progressive encoding is only applicable to png image format
-            // TODO(xlai): Progressive encoding on jpeg and webp image formats (crbug.com/571398, crbug.com/571399)
-            progressiveEncodeImageOnEncoderThread();
-        } else {
-            nonprogressiveEncodeImageOnEncoderThread(quality);
-        }
-    }
-}
-
-bool CanvasAsyncBlobCreator::initializeEncodeImageOnEncoderThread()
-{
-    if (m_cancelled) {
-        scheduleClearSelfRefOnMainThread();
-        return false;
-    }
-
-    if (m_mimeType == "image/png") {
-        m_encoderState = PNGImageEncoderState::create(m_size, m_encodedImage.get());
-        if (m_cancelled) {
-            scheduleClearSelfRefOnMainThread();
-            return false;
-        }
-        if (!m_encoderState) {
-            scheduleCreateNullptrAndCallOnMainThread();
-            return false;
-        }
-    } // else, do nothing; as encoding on other image formats are not progressive
-    return true;
-}
 
-void CanvasAsyncBlobCreator::nonprogressiveEncodeImageOnEncoderThread(double quality)
-{
     if (ImageDataBuffer(m_size, m_data->data()).encodeImage(m_mimeType, quality, m_encodedImage.get())) {
         scheduleCreateBlobAndCallOnMainThread();
     } else {
@@ -207,32 +132,6 @@ void CanvasAsyncBlobCreator::nonprogressiveEncodeImageOnEncoderThread(double qua
     }
 }
 
-void CanvasAsyncBlobCreator::progressiveEncodeImageOnEncoderThread()
-{
-    unsigned char* inputPixels = m_data->data() + m_pixelRowStride * m_numRowsCompleted;
-    for (int y = 0; y < m_size.height() && !m_cancelled; ++y) {
-        PNGImageEncoder::writeOneRowToPng(inputPixels, m_encoderState.get());
-        inputPixels += m_pixelRowStride;
-    }
-    if (m_cancelled) {
-        scheduleClearSelfRefOnMainThread();
-        return;
-    }
-
-    PNGImageEncoder::finalizePng(m_encoderState.get());
-    if (m_cancelled) {
-        scheduleClearSelfRefOnMainThread();
-        return;
-    }
-
-    scheduleCreateBlobAndCallOnMainThread();
-}
-
-void CanvasAsyncBlobCreator::createContextObserver(ExecutionContext* executionContext)
-{
-    m_contextObserver = adoptPtrWillBeNoop(new ContextObserver(executionContext, this));
-}
-
 void CanvasAsyncBlobCreator::clearSelfReference()
 {
     // Some persistent members in CanvasAsyncBlobCreator can only be destroyed