Add WorkerSettings to expose certain flag values in WorkerGlobalScope

third_party/WebKit/Source/modules/offscreencanvas2d/OffscreenCanvasRenderingContext2D.cpp

Index: third_party/WebKit/Source/modules/offscreencanvas2d/OffscreenCanvasRenderingContext2D.cpp
diff --git a/third_party/WebKit/Source/modules/offscreencanvas2d/OffscreenCanvasRenderingContext2D.cpp b/third_party/WebKit/Source/modules/offscreencanvas2d/OffscreenCanvasRenderingContext2D.cpp
index 2863df303511f9dbf33204113c5724b874e8a994..895e12660fb9acd615e07944b62de2061ffae4a6 100644
--- a/third_party/WebKit/Source/modules/offscreencanvas2d/OffscreenCanvasRenderingContext2D.cpp
+++ b/third_party/WebKit/Source/modules/offscreencanvas2d/OffscreenCanvasRenderingContext2D.cpp
@@ -6,6 +6,8 @@
 
 #include "bindings/modules/v8/OffscreenCanvasRenderingContext2DOrWebGLRenderingContextOrWebGL2RenderingContext.h"
 #include "core/frame/ImageBitmap.h"
+#include "core/frame/Settings.h"
+#include "core/workers/WorkerSettings.h"
 #include "platform/graphics/ImageBuffer.h"
 #include "platform/graphics/StaticBitmapImage.h"
 #include "wtf/Assertions.h"
@@ -18,10 +20,21 @@ OffscreenCanvasRenderingContext2D::~OffscreenCanvasRenderingContext2D()
 {
 }
 
-OffscreenCanvasRenderingContext2D::OffscreenCanvasRenderingContext2D(OffscreenCanvas* canvas, const CanvasContextCreationAttributes& attrs)
+OffscreenCanvasRenderingContext2D::OffscreenCanvasRenderingContext2D(ScriptState* scriptState, OffscreenCanvas* canvas, const CanvasContextCreationAttributes& attrs)
     : CanvasRenderingContext(nullptr, canvas)
     , m_hasAlpha(attrs.alpha())
 {
+    ExecutionContext* executionContext = scriptState->getExecutionContext();
+    if (executionContext->isDocument()) {
+        m_disableReadingFromCanvas = toDocument(executionContext)->settings()->disableReadingFromCanvas();
+        return;
+    }
+
+    WorkerSettings* workerSettings = WorkerSettings::from(executionContext);
+    if (workerSettings)
+        m_disableReadingFromCanvas = workerSettings->disableReadingFromCanvas();
+    else
+        m_disableReadingFromCanvas = false;
 }
 
 DEFINE_TRACE(OffscreenCanvasRenderingContext2D)
@@ -33,7 +46,7 @@ DEFINE_TRACE(OffscreenCanvasRenderingContext2D)
 // BaseRenderingContext2D implementation
 bool OffscreenCanvasRenderingContext2D::originClean() const
 {
-    return getOffscreenCanvas()->originClean();
+    return getOffscreenCanvas()->originClean() && !m_disableReadingFromCanvas;
 }
 
 void OffscreenCanvasRenderingContext2D::setOriginTainted()