Remove WebGLObject maps from WebGLRenderingContextBase and WebGLContextGroup.

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

Index: third_party/WebKit/Source/modules/webgl/WebGLContextObject.cpp
diff --git a/third_party/WebKit/Source/modules/webgl/WebGLContextObject.cpp b/third_party/WebKit/Source/modules/webgl/WebGLContextObject.cpp
index b42f12265843bac74136fd6d539cb72b2a9647cb..0965b282acdc64753507e0644b15700d7d615630 100644
--- a/third_party/WebKit/Source/modules/webgl/WebGLContextObject.cpp
+++ b/third_party/WebKit/Source/modules/webgl/WebGLContextObject.cpp
@@ -32,15 +32,18 @@ namespace blink {
 WebGLContextObject::WebGLContextObject(WebGLRenderingContextBase* context)
     : WebGLObject(context), m_context(context) {}
 
-WebGLContextObject::~WebGLContextObject() {}
-
-void WebGLContextObject::detachContext() {
-  detach();
-  if (m_context) {
-    deleteObject(m_context->contextGL());
-    m_context->removeContextObject(this);
-    m_context = nullptr;
-  }
+bool WebGLContextObject::validate(
+    const WebGLContextGroup*,
+    const WebGLRenderingContextBase* context) 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 context == m_context &&
+         cachedNumberOfContextLosses() == context->numberOfContextLosses();
+}
+
+uint32_t WebGLContextObject::currentNumberOfContextLosses() const {
+  return m_context->numberOfContextLosses();
 }
 
 gpu::gles2::GLES2Interface* WebGLContextObject::getAGLInterface() const {