[Blink, RemotePlaybackAPI] Create WebRemotePlaybackClient in HTMLMediaElement ctor to avoid lazy in…

third_party/WebKit/Source/core/html/HTMLMediaElement.cpp

Index: third_party/WebKit/Source/core/html/HTMLMediaElement.cpp
diff --git a/third_party/WebKit/Source/core/html/HTMLMediaElement.cpp b/third_party/WebKit/Source/core/html/HTMLMediaElement.cpp
index be3968b5e56dd5f10eacdd3546f0864afe956048..f355c16a6d474c4ba5d17264b93cd18204c0c239 100644
--- a/third_party/WebKit/Source/core/html/HTMLMediaElement.cpp
+++ b/third_party/WebKit/Source/core/html/HTMLMediaElement.cpp
@@ -96,6 +96,7 @@
 #include "wtf/PtrUtil.h"
 #include "wtf/text/CString.h"
 #include <limits>
+#include <v8.h>
 
 #ifndef BLINK_MEDIA_LOG
 #define BLINK_MEDIA_LOG DVLOG(3)
@@ -475,6 +476,15 @@ HTMLMediaElement::HTMLMediaElement(const QualifiedName& tagName,
     m_lockedPendingUserGesture = true;
   }
 
+  LocalFrame* frame = document.frame();
+  if (frame) {
+    v8::Isolate* isolate = v8::Isolate::GetCurrent();
+    ScriptState* scriptState = ScriptState::from(isolate->GetCurrentContext());

[haraken, 2016/11/08 23:50:40]

You shouldn't use isolate->GetCurrentContext() unless you're pretty sure that
this code is always called while you're already in a correct context.

Instead, you can pass in a ScriptState* parameter using
[ConstructorCallWith=ScriptState].

(Actually passing ScriptState* to HTMLMediaElement and then to RemotePlayback is
wrong for a complicated reason
(https://groups.google.com/a/chromium.org/d/topic/platform-architecture-dev/nB...),
but that's a separate discussion.)

[whywhat, 2016/11/09 00:22:02]

Tests actually crash because context seems to be empty when the document is
being parsed and HTMLMediaElement is being created.
So in my case I only keep ScriptState to run an async callback. Should I try to
pass ScriptState to the callback then? Does ScriptState support being passed
around like a bound object?

+    m_remotePlaybackClient =
+        frame->loader().client()->createWebRemotePlaybackClient(scriptState,
+                                                                *this);
+  }
+
   setHasCustomStyleCallbacks();
   addElementToDocumentMap(this, &document);
 
@@ -3939,11 +3949,6 @@ void HTMLMediaElement::updatePositionNotificationRegistration() {
   m_autoplayHelper->updatePositionNotificationRegistration();
 }
 
-void HTMLMediaElement::setRemotePlaybackClient(
-    WebRemotePlaybackClient* client) {
-  m_remotePlaybackClient = client;
-}
-
 // TODO(liberato): remove once autoplay gesture override experiment concludes.
 void HTMLMediaElement::triggerAutoplayViewportCheckForTesting() {
   if (FrameView* view = document().view())