Pass ResizeObserver as 'this' to callback

I had to implement a custom callback dispatch handler.
Used MutationObserver code as a template.

Added a test case.

BUG=641353

Review-Url: https://codereview.chromium.org/2303893003
Cr-Commit-Position: refs/heads/master@{#417464}

third_party/WebKit/LayoutTests/resize-observer/observe.html

@@ -164,6 +164,31 @@ function test6() {
   return promise;
 }
 
+function test7() {
+  let harnessTest = async_test("test7: callback.this");
+  let resolvePromise;
+  let ro = new ResizeObserver( function(entries, obs)  {
+    let callbackThis = this;
+    resolvePromise();
+    harnessTest.step(() => {
+      assert_equals(callbackThis, ro, "callback.this is ResizeObserver");
+      assert_equals(obs, ro, "2nd argument is ResizeObserver");
+      ro.disconnect();
+      // every reference to RO must be null before test completes
+      // to avoid triggering test leak-detection
+      ro = null;
+      callbackThis = null;
+      obs = null;
+      harnessTest.done();
+     });
+    }
+  );
+  ro.observe(t1);
+
+  return new Promise( (resolve, reject) => {
+    resolvePromise = resolve;
+  });
+}
 let guard = async_test('guard');
 test0()
   .then(() => { return test1(); })
@@ -172,6 +197,7 @@ test0()
   .then(() => { return test4(); })
   .then(() => { return test5(); })
   .then(() => { return test6(); })
+  .then(() => { return test7(); })
   .then(() => { guard.done(); });
 
 </script>

third_party/WebKit/Source/bindings/bindings.gni

@@ -189,6 +189,7 @@ bindings_core_v8_files =
                     "core/v8/V8PersistentValueVector.h",
                     "core/v8/V8PrivateProperty.cpp",
                     "core/v8/V8PrivateProperty.h",
+                    "core/v8/V8ResizeObserverCallbackCustom.cpp",
                     "core/v8/V8ScriptRunner.cpp",
                     "core/v8/V8ScriptRunner.h",
                     "core/v8/V8StringResource.cpp",

third_party/WebKit/Source/bindings/core/v8/V8ResizeObserverCallbackCustom.cpp

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "bindings/core/v8/V8ResizeObserverCallback.h"
+
+#include "bindings/core/v8/ScriptController.h"
+#include "bindings/core/v8/V8Binding.h"
+#include "bindings/core/v8/V8ResizeObserver.h"
+#include "bindings/core/v8/V8ResizeObserverEntry.h"
+#include "core/dom/ExecutionContext.h"
+
+namespace blink {
+
+void V8ResizeObserverCallback::handleEvent(const HeapVector<Member<ResizeObserverEntry>>& entries, ResizeObserver* observer)
+{
+    if (!canInvokeCallback())
+        return;
+
+    v8::Isolate* isolate = m_scriptState->isolate();
+
+    if (!m_scriptState->contextIsValid())
+        return;
+    ScriptState::Scope scope(m_scriptState.get());
+
+    if (m_callback.isEmpty())
+        return;
+
+    v8::Local<v8::Value> observerHandle = toV8(observer, m_scriptState->context()->Global(), m_scriptState->isolate());
+    if (!observerHandle->IsObject())
+        return;
+
+    v8::Local<v8::Object> thisObject = v8::Local<v8::Object>::Cast(observerHandle);
+    v8::Local<v8::Value> entriesHandle = toV8(entries, m_scriptState->context()->Global(), m_scriptState->isolate());
+    if (entriesHandle.IsEmpty())
+        return;
+    v8::Local<v8::Value> argv[] = { entriesHandle, observerHandle };
+
+    v8::TryCatch exceptionCatcher(m_scriptState->isolate());
+    exceptionCatcher.SetVerbose(true);
+    V8ScriptRunner::callFunction(m_callback.newLocal(isolate), getExecutionContext(), thisObject, WTF_ARRAY_LENGTH(argv), argv, isolate);
+}
+
+
+} // namespace blink

third_party/WebKit/Source/core/observer/ResizeObserverCallback.idl

@@ -3,5 +3,5 @@
 // found in the LICENSE file.
 
 callback interface ResizeObserverCallback {
-    void handleEvent(sequence<ResizeObserverEntry> entries, ResizeObserver observer);
+    [Custom] void handleEvent(sequence<ResizeObserverEntry> entries, ResizeObserver observer);
 };