Oilpan: move 2D Canvas and WebGL objects to the heap.

Source/core/html/canvas/WebGLContextObject.cpp

Index: Source/core/html/canvas/WebGLContextObject.cpp
diff --git a/Source/core/html/canvas/WebGLContextObject.cpp b/Source/core/html/canvas/WebGLContextObject.cpp
index 4a85e57771adbec4d0e337f9af49562cebbb17bf..b8316704b9f77ce20f5d270efdf3e888d63d7b80 100644
--- a/Source/core/html/canvas/WebGLContextObject.cpp
+++ b/Source/core/html/canvas/WebGLContextObject.cpp
@@ -28,19 +28,25 @@
 #include "core/html/canvas/WebGLContextObject.h"
 
 #include "core/html/canvas/WebGLRenderingContextBase.h"
+#include "core/html/canvas/WebGLSharedWebGraphicsContext3D.h"
 
 namespace blink {
 
 WebGLContextObject::WebGLContextObject(WebGLRenderingContextBase* context)
     : WebGLObject(context)
     , m_context(context)
+#if ENABLE(OILPAN)
+    , m_sharedWebGraphicsContext3D(context->sharedWebGraphicsContext3D())
+#endif
 {
 }
 
 WebGLContextObject::~WebGLContextObject()
 {
+#if !ENABLE(OILPAN)
     if (m_context)
         m_context->removeContextObject(this);
+#endif
 }
 
 void WebGLContextObject::detachContext()
@@ -49,13 +55,26 @@ void WebGLContextObject::detachContext()
     if (m_context) {
         deleteObject(m_context->webContext());
         m_context->removeContextObject(this);
-        m_context = 0;
+        m_context = nullptr;
+#if ENABLE(OILPAN)
+        m_sharedWebGraphicsContext3D.clear();
+#endif
     }
 }
 
 blink::WebGraphicsContext3D* WebGLContextObject::getAWebGraphicsContext3D() const
 {
+#if ENABLE(OILPAN)
+    return m_sharedWebGraphicsContext3D ? m_sharedWebGraphicsContext3D->webContext() : 0;

[haraken, 2014/07/22 03:46:10]

Just help me understand: When does it happen that m_sharedWebGraphicsContext3D
is not 0 but m_sharedWebGraphicsContext3D->webContext() returns 0? I wonder why
we need to 0 checks:

- The first check in WebGLContextObject::getAWebGraphicsContext3D().
- The second check in WebGLSharedWebGraphicsContext3D::webContext().

[sof, 2014/07/22 06:15:21]

This seems like a trifling matter. You can dispose() of a
WebGLSharedWebGraphicsContext3D to clear out the buffer, which is why it makes
sense to explicitly null check in webContext(). Similarly, you can detach a
WebGLContextObject and clear out the m_sharedWebGraphicsContext3D reference.

+#else
     return m_context ? m_context->webContext() : 0;
+#endif
+}
+
+void WebGLContextObject::trace(Visitor* visitor)
+{
+    visitor->trace(m_context);
+    WebGLObject::trace(visitor);
 }
 
 }