Introduce DOMWindowClient

The lifetime of ExecutionContext and DOMWindow is a bit different.
In common case, they get detached at the same timing but in a case where
a frame navigates from an initial empty document to another same-origin document,
the ExecutionContext gets detached but the DOMWindow is reused.
Due to the (subtle) difference, we need DOMWindowClient in addition to ContextClient.

ContextClient is a client for objects that want to observe ExecutionContext.
DOMWindowClient is a client for objects that want to observe DOMWindow.

This CL uses DOMWindowClient for Navigator.

BUG=610176

Review-Url: https://codereview.chromium.org/2629493004
Cr-Commit-Position: refs/heads/master@{#443216}

third_party/WebKit/Source/core/dom/ContextLifecycleObserver.cpp

@@ -5,10 +5,14 @@
 #include "core/dom/ContextLifecycleObserver.h"
 
 #include "core/dom/Document.h"
+#include "core/frame/LocalDOMWindow.h"
 #include "core/frame/LocalFrame.h"
 
 namespace blink {
 
+ContextClient::ContextClient(ExecutionContext* executionContext)
+    : m_executionContext(executionContext) {}
+
 ContextClient::ContextClient(LocalFrame* frame)
     : m_executionContext(frame ? frame->document() : nullptr) {}
 
@@ -33,4 +37,22 @@ LocalFrame* ContextLifecycleObserver::frame() const {
              ? toDocument(getExecutionContext())->frame()
              : nullptr;
 }
+
+DOMWindowClient::DOMWindowClient(LocalDOMWindow* window)
+    : m_domWindow(window) {}
+
+DOMWindowClient::DOMWindowClient(LocalFrame* frame)
+    : m_domWindow(frame ? frame->domWindow() : nullptr) {}
+
+LocalDOMWindow* DOMWindowClient::domWindow() const {
+  return m_domWindow && m_domWindow->frame() ? m_domWindow : nullptr;
+}
+
+LocalFrame* DOMWindowClient::frame() const {
+  return m_domWindow ? m_domWindow->frame() : nullptr;
+}
+
+DEFINE_TRACE(DOMWindowClient) {
+  visitor->trace(m_domWindow);
+}
 }

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

@@ -33,17 +33,15 @@
 
 namespace blink {
 
+class LocalDOMWindow;
 class LocalFrame;
 
-// ContextClient and ContextLifecycleObserver are helpers to associate a
-// class with an ExecutionContext. ContextLifecycleObserver provides an
-// additional contextDestroyed() hook to execute cleanup code when a
-// context is destroyed. Prefer the simpler ContextClient when possible.
+// ContextClient and ContextLifecycleObserver are helpers to associate an
+// object with an ExecutionContext.
 //
-// getExecutionContext() returns null after the observing context is detached.
-// frame() returns null after the observing context is detached or if the
-// context doesn't have a frame (i.e., if the context is not a Document).
-
+// - getExecutionContext() returns null after the context is detached.
+// - frame() is a syntax sugar for getExecutionContext()->frame(). It returns
+//   null after the context is detached or the context is not a Document.
 class CORE_EXPORT ContextClient : public GarbageCollectedMixin {
  public:
   ExecutionContext* getExecutionContext() const;
@@ -52,14 +50,16 @@ class CORE_EXPORT ContextClient : public GarbageCollectedMixin {
   DECLARE_VIRTUAL_TRACE();
 
  protected:
-  explicit ContextClient(ExecutionContext* executionContext)
-      : m_executionContext(executionContext) {}
+  explicit ContextClient(ExecutionContext*);
   explicit ContextClient(LocalFrame*);
 
  private:
   WeakMember<ExecutionContext> m_executionContext;
 };
 
+// ContextLifecycleObserver provides an additional contextDestroyed() hook
+// to execute cleanup code when a context is destroyed. Prefer the simpler
+// ContextClient when possible.
 class CORE_EXPORT ContextLifecycleObserver
     : public LifecycleObserver<ExecutionContext, ContextLifecycleObserver> {
  public:
@@ -82,6 +82,40 @@ class CORE_EXPORT ContextLifecycleObserver
   Type m_observerType;
 };
 
+// DOMWindowClient is a helper to associate an object with a LocalDOMWindow.
+//
+// - domWindow() returns null after the window is detached.
+// - frame() is a syntax sugar for domWindow()->frame(). It returns
+//   null after the window is detached.
+//
+// If the object is a per-ExecutionContext thing, use ContextClient/
+// ContextLifecycleObserver. If the object is a per-DOMWindow thing, use
+// DOMWindowClient. Basically, DOMWindowClient is expected to be used (only)
+// for objects directly held by LocalDOMWindow. Other objects should use
+// ContextClient/ContextLifecycleObserver.
+//
+// There is a subtle difference between the timing when the context gets
+// detached and the timing when the window gets detached. In common cases,
+// these two happen at the same timing. The only exception is a case where
+// a frame navigates from an initial empty document to another same-origin
+// document. In this case, a Document is recreated but a DOMWindow is reused.
+// Hence, in the navigated document ContextClient::getExecutionContext()
+// returns null while DOMWindowClient::domWindow() keeps returning the window.
+class CORE_EXPORT DOMWindowClient : public GarbageCollectedMixin {
+ public:
+  LocalDOMWindow* domWindow() const;
+  LocalFrame* frame() const;
+
+  DECLARE_VIRTUAL_TRACE();
+
+ protected:
+  explicit DOMWindowClient(LocalDOMWindow*);
+  explicit DOMWindowClient(LocalFrame*);
+
+ private:
+  WeakMember<LocalDOMWindow> m_domWindow;
+};
+
 }  // namespace blink
 
 #endif  // ContextLifecycleObserver_h

third_party/WebKit/Source/core/frame/LocalDOMWindow.cpp

@@ -53,6 +53,7 @@
 #include "core/fetch/ResourceFetcher.h"
 #include "core/frame/BarProp.h"
 #include "core/frame/DOMVisualViewport.h"
+#include "core/frame/DOMWindowProperty.h"
 #include "core/frame/EventHandlerRegistry.h"
 #include "core/frame/FrameConsole.h"
 #include "core/frame/FrameView.h"

third_party/WebKit/Source/core/frame/Navigator.cpp

@@ -36,7 +36,7 @@
 
 namespace blink {
 
-Navigator::Navigator(LocalFrame* frame) : DOMWindowProperty(frame) {}
+Navigator::Navigator(LocalFrame* frame) : DOMWindowClient(frame) {}
 
 String Navigator::productSub() const {
   return "20030107";
@@ -98,7 +98,7 @@ Vector<String> Navigator::languages() {
 }
 
 DEFINE_TRACE(Navigator) {
-  DOMWindowProperty::trace(visitor);
+  DOMWindowClient::trace(visitor);
   Supplementable<Navigator>::trace(visitor);
 }
 

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

@@ -22,7 +22,7 @@
 
 #include "bindings/core/v8/ScriptWrappable.h"
 #include "core/CoreExport.h"
-#include "core/frame/DOMWindowProperty.h"
+#include "core/dom/ContextLifecycleObserver.h"
 #include "core/frame/NavigatorCPU.h"
 #include "core/frame/NavigatorID.h"
 #include "core/frame/NavigatorLanguage.h"
@@ -41,7 +41,7 @@ class CORE_EXPORT Navigator final : public GarbageCollected<Navigator>,
                                     public NavigatorLanguage,
                                     public NavigatorOnLine,
                                     public ScriptWrappable,
-                                    public DOMWindowProperty,
+                                    public DOMWindowClient,
                                     public Supplementable<Navigator> {
   DEFINE_WRAPPERTYPEINFO();
   USING_GARBAGE_COLLECTED_MIXIN(Navigator);