Add a pure virtual method to the GarbageCollectedMixin class

It's easy to miss adding USING_GARBAGE_COLLECTED_MIXIN macros to classes
that inherit from GarbageCollectedMixin. To avoid the programming error,
this CL adds a pure virtual method to the GarbageCollectedMixin class.
If we miss the USING_GARBAGE_COLLECTED_MIXIN macro, we'll hit a compile error.

This CL also fixes existing programming errors.

BUG=420515

Review URL: https://codereview.chromium.org/659953002

git-svn-id: svn://svn.chromium.org/blink/trunk@183799 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Source/core/dom/DocumentParserClient.h

@@ -14,6 +14,8 @@ public:
     // This callback is called when all data pushed to parser has been consumed.
     virtual void notifyParserStopped() = 0;
 
+    virtual void trace(Visitor*) { }
+
 protected:
     DocumentParserClient() { }
 };

third_party/WebKit/Source/core/frame/LocalFrame.h

@@ -65,6 +65,7 @@ namespace blink {
     class VisiblePosition;
 
     class LocalFrame : public Frame, public WillBeHeapSupplementable<LocalFrame> {
+        WILL_BE_USING_GARBAGE_COLLECTED_MIXIN(LocalFrame);
     public:
         static PassRefPtrWillBeRawPtr<LocalFrame> create(FrameLoaderClient*, FrameHost*, FrameOwner*);
 

third_party/WebKit/Source/core/html/imports/HTMLImportLoader.cpp

@@ -233,6 +233,7 @@ void HTMLImportLoader::trace(Visitor* visitor)
     visitor->trace(m_document);
     visitor->trace(m_writer);
     visitor->trace(m_microtaskQueue);
+    DocumentParserClient::trace(visitor);
 }
 
 } // namespace blink

third_party/WebKit/Source/core/html/imports/HTMLImportLoader.h

@@ -55,6 +55,7 @@ class HTMLImportsController;
 //
 //
 class HTMLImportLoader final : public NoBaseWillBeGarbageCollectedFinalized<HTMLImportLoader>, public ResourceOwner<RawResource>, public DocumentParserClient {
+    WILL_BE_USING_GARBAGE_COLLECTED_MIXIN(HTMLImportLoader);
 public:
     enum State {
         StateLoading,

third_party/WebKit/Source/core/xml/XMLHttpRequest.cpp

@@ -1662,6 +1662,7 @@ void XMLHttpRequest::trace(Visitor* visitor)
     visitor->trace(m_upload);
     visitor->trace(m_blobLoader);
     XMLHttpRequestEventTarget::trace(visitor);
+    DocumentParserClient::trace(visitor);
 }
 
 } // namespace blink

third_party/WebKit/Source/modules/presentation/Presentation.h

@@ -15,6 +15,7 @@ class Presentation final
     , public EventTargetWithInlineData
     , public ContextLifecycleObserver {
     DEFINE_EVENT_TARGET_REFCOUNTING_WILL_BE_REMOVED(RefCountedGarbageCollected<Presentation>);
+    WILL_BE_USING_GARBAGE_COLLECTED_MIXIN(Presentation);
     DEFINE_WRAPPERTYPEINFO();
 public:
     static Presentation* create(ExecutionContext*);

third_party/WebKit/Source/modules/screen_orientation/ScreenOrientationDispatcher.h

@@ -19,6 +19,7 @@ namespace blink {
 // ScreenOrientationDispatcher is listening, that means that the platform should
 // be polling if required.
 class ScreenOrientationDispatcher final : public GarbageCollectedFinalized<ScreenOrientationDispatcher>, public PlatformEventDispatcher {
+    USING_GARBAGE_COLLECTED_MIXIN(ScreenOrientationDispatcher);
 public:
     static ScreenOrientationDispatcher& instance();
 

third_party/WebKit/Source/platform/heap/Visitor.h

@@ -585,8 +585,8 @@ template<typename T> bool ObjectAliveTrait<T>::isHeapObjectAlive(Visitor* visito
 
 class PLATFORM_EXPORT GarbageCollectedMixin {
 public:
-    virtual void adjustAndMark(Visitor*) const { };
-    virtual bool isHeapObjectAlive(Visitor*) const { return true; };
+    virtual void adjustAndMark(Visitor*) const = 0;
+    virtual bool isHeapObjectAlive(Visitor*) const = 0;
     virtual void trace(Visitor*) { }
 };