Make CanvasRenderingContext not inherit from ActiveDOMObject

third_party/WebKit/Source/core/html/HTMLCanvasElement.cpp

Index: third_party/WebKit/Source/core/html/HTMLCanvasElement.cpp
diff --git a/third_party/WebKit/Source/core/html/HTMLCanvasElement.cpp b/third_party/WebKit/Source/core/html/HTMLCanvasElement.cpp
index 63d691d071e28e0340a84d5aae3a19f0c0839ca3..f0c2f5bb0e85aca9b5f2d33dc1db886b48a4252b 100644
--- a/third_party/WebKit/Source/core/html/HTMLCanvasElement.cpp
+++ b/third_party/WebKit/Source/core/html/HTMLCanvasElement.cpp
@@ -937,6 +937,7 @@ void HTMLCanvasElement::didChangeVisibilityState(PageVisibilityState visibility)
 {
     if (!m_context)
         return;
+
     bool hidden = visibility != PageVisibilityStateVisible;
     m_context->setIsHidden(hidden);
     if (hidden) {
@@ -947,6 +948,12 @@ void HTMLCanvasElement::didChangeVisibilityState(PageVisibilityState visibility)
     }
 }
 
+void HTMLCanvasElement::willDetachDocument()
+{
+    if (m_context)
+        m_context->stop();
+}
+
 void HTMLCanvasElement::styleDidChange(const ComputedStyle* oldStyle, const ComputedStyle& newStyle)
 {
     if (m_context)
@@ -956,8 +963,6 @@ void HTMLCanvasElement::styleDidChange(const ComputedStyle* oldStyle, const Comp
 void HTMLCanvasElement::didMoveToNewDocument(Document& oldDocument)
 {
     setObservedDocument(document());
-    if (m_context)
-        m_context->didMoveToNewDocument(&document());
     HTMLElement::didMoveToNewDocument(oldDocument);
 }