Make OffscreenCanvas an EventTarget

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

Index: third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.cpp
diff --git a/third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.cpp b/third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.cpp
index ca13517d9d8e67ef81a1db32ef5e8b1652581d42..0b557f5fad384cb75028e2c13e67df1c0dd77745 100644
--- a/third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.cpp
+++ b/third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.cpp
@@ -972,11 +972,13 @@ WebGLRenderingContextBase::WebGLRenderingContextBase(
     OffscreenCanvas* passedOffscreenCanvas,
     std::unique_ptr<WebGraphicsContext3DProvider> contextProvider,
     const CanvasContextCreationAttributes& requestedAttributes,
+    ExecutionContext* executionContext,
     unsigned version)
     : WebGLRenderingContextBase(nullptr,
                                 passedOffscreenCanvas,
                                 std::move(contextProvider),
                                 requestedAttributes,
+                                executionContext,
                                 version) {}
 
 WebGLRenderingContextBase::WebGLRenderingContextBase(
@@ -988,6 +990,7 @@ WebGLRenderingContextBase::WebGLRenderingContextBase(
                                 nullptr,
                                 std::move(contextProvider),
                                 requestedAttributes,
+                                nullptr,
                                 version) {}
 
 WebGLRenderingContextBase::WebGLRenderingContextBase(
@@ -995,6 +998,7 @@ WebGLRenderingContextBase::WebGLRenderingContextBase(
     OffscreenCanvas* passedOffscreenCanvas,
     std::unique_ptr<WebGraphicsContext3DProvider> contextProvider,
     const CanvasContextCreationAttributes& requestedAttributes,
+    ExecutionContext* executionContext,
     unsigned version)
     : CanvasRenderingContext(passedCanvas,
                              passedOffscreenCanvas,
@@ -1023,7 +1027,8 @@ WebGLRenderingContextBase::WebGLRenderingContextBase(
       m_isOESTextureHalfFloatFormatsTypesAdded(false),
       m_isWebGLDepthTextureFormatsTypesAdded(false),
       m_isEXTsRGBFormatsTypesAdded(false),
-      m_version(version) {
+      m_version(version),
+      m_executionContext(executionContext) {
   ASSERT(contextProvider);
 
   m_contextGroup = WebGLContextGroup::create();
@@ -7297,7 +7302,10 @@ bool WebGLRenderingContextBase::validateDrawElements(const char* functionName,
 void WebGLRenderingContextBase::dispatchContextLostEvent(TimerBase*) {
   WebGLContextEvent* event = WebGLContextEvent::create(
       EventTypeNames::webglcontextlost, false, true, "");
-  canvas()->dispatchEvent(event);
+  if (getOffscreenCanvas())
+    getOffscreenCanvas()->dispatchEvent(event);
+  else
+    canvas()->dispatchEvent(event);
   m_restoreAllowed = event->defaultPrevented();
   if (m_restoreAllowed && !m_isHidden) {
     if (m_autoRecoveryMethod == Auto)
@@ -7596,6 +7604,7 @@ DEFINE_TRACE(WebGLRenderingContextBase) {
   visitor->trace(m_renderbufferBinding);
   visitor->trace(m_textureUnits);
   visitor->trace(m_extensions);
+  visitor->trace(m_executionContext);
   CanvasRenderingContext::trace(visitor);
 }