Remove WebGLObject maps from WebGLRenderingContextBase and WebGLContextGroup.

third_party/WebKit/Source/modules/webgl/WebGLSharedObject.cpp

Index: third_party/WebKit/Source/modules/webgl/WebGLSharedObject.cpp
diff --git a/third_party/WebKit/Source/modules/webgl/WebGLSharedObject.cpp b/third_party/WebKit/Source/modules/webgl/WebGLSharedObject.cpp
index 4cc3717bf4967e31448970f07924bb323dd52ec7..074fcbc4685f2a5c9d1d47a454df72f607404848 100644
--- a/third_party/WebKit/Source/modules/webgl/WebGLSharedObject.cpp
+++ b/third_party/WebKit/Source/modules/webgl/WebGLSharedObject.cpp
@@ -31,24 +31,33 @@
 namespace blink {
 
 WebGLSharedObject::WebGLSharedObject(WebGLRenderingContextBase* context)
-    : WebGLObject(context), m_contextGroup(context->contextGroup()) {}
-
-WebGLSharedObject::~WebGLSharedObject() {
-  if (m_contextGroup)
-    m_contextGroup->removeObject(this);
+    : WebGLObject(context), m_contextGroup(this, context->contextGroup()) {}
+
+bool WebGLSharedObject::validate(const WebGLContextGroup* contextGroup,
+                                 const WebGLRenderingContextBase*) const {
+  // The contexts and context groups no longer maintain references to all
+  // the objects they ever created, so there's no way to invalidate them
+  // eagerly during context loss. The invalidation is discovered lazily.
+  return contextGroup == m_contextGroup &&
+         cachedNumberOfContextLosses() == contextGroup->numberOfContextLosses();
 }
 
-void WebGLSharedObject::detachContextGroup() {
-  detach();
-  if (m_contextGroup) {
-    deleteObject(nullptr);
-    m_contextGroup->removeObject(this);
-    m_contextGroup = nullptr;
-  }
+uint32_t WebGLSharedObject::currentNumberOfContextLosses() const {
+  return m_contextGroup->numberOfContextLosses();
 }
 
 gpu::gles2::GLES2Interface* WebGLSharedObject::getAGLInterface() const {

[haraken, 2016/12/05 05:15:59]

Don't we need to have a call path that clears m_contextGroup when WebGL object
gets destructed?

[Ken Russell (switch to Gerrit), 2016/12/05 06:03:40]

Actually, looking at this code again, m_contextGroup is guaranteed to be
non-null. WebGLSharedObject maintains a strong reference to it. We don't need to
zero it out in WebGLSharedObject's destructor.

As we discussed in https://codereview.chromium.org/2548153002/ , the only thing
that might happen is that all of m_contextGroup's weak references might be
cleared.

Should I change this code to:

  return m_contextGroup->getAGLInterface();

?

[haraken, 2016/12/05 06:08:40]

Sounds nicer.

[Ken Russell (switch to Gerrit), 2016/12/05 06:36:20]

Will fix.

   return m_contextGroup ? m_contextGroup->getAGLInterface() : nullptr;
 }
 
+DEFINE_TRACE(WebGLSharedObject) {
+  visitor->trace(m_contextGroup);
+  WebGLObject::trace(visitor);
+}
+
+DEFINE_TRACE_WRAPPERS(WebGLSharedObject) {
+  visitor->traceWrappers(m_contextGroup);
+  WebGLObject::traceWrappers(visitor);
+}
+
 }  // namespace blink