Create only a single LegacyRenderWidgetHostHWND per WebContentsViewAura.

content/browser/renderer_host/legacy_render_widget_host_win.h

Index: content/browser/renderer_host/legacy_render_widget_host_win.h
diff --git a/content/browser/renderer_host/legacy_render_widget_host_win.h b/content/browser/renderer_host/legacy_render_widget_host_win.h
index ce08a0e4bb6cdbb993a94ec5eb9a98b3c14f73f8..78ea4defde413f5ff3b44eaa4aead5353b1eea49 100644
--- a/content/browser/renderer_host/legacy_render_widget_host_win.h
+++ b/content/browser/renderer_host/legacy_render_widget_host_win.h
@@ -20,7 +20,8 @@ class WindowEventTarget;
 }
 
 namespace content {
-class BrowserAccessibilityManagerWin;
+class BrowserAccessibilityManager;
+class LegacyRenderWidgetHostHWND;
 class RenderWidgetHostViewAura;
 
 // Reasons for the existence of this class outlined below:-
@@ -40,6 +41,18 @@ class RenderWidgetHostViewAura;
 //    fail.
 //    We should look to get rid of this code when all of the above are fixed.
 
+// A delegate interface for LegacyRenderWidgetHostHWND to query its owner.

[ananta, 2014/07/14 18:51:08]

The comment here needs to be reworded?. query its owner is not the functionality
exposed by this interface?

[dmazzoni, 2014/07/29 23:03:05]

Done.

+class CONTENT_EXPORT LegacyRenderWidgetHostHWNDDelegate {
+ public:
+  // Get the root BrowserAccessibilityManager representing the accessible
+  // state of this WebContents. This should always return a valid object,
+  // but the object may change as the user navigates.
+  virtual BrowserAccessibilityManager* GetRootBrowserAccessibilityManager() = 0;
+
+  // This will be called when the HWND is destroyed.
+  virtual void OnLegacyHwndDestroyed(LegacyRenderWidgetHostHWND* owner) = 0;
+};
+
 // This class implements a child HWND with the same size as the content area,
 // that delegates its accessibility implementation to the root of the
 // BrowserAccessibilityManager tree. This HWND is hooked up as the parent of
@@ -51,6 +64,8 @@ class CONTENT_EXPORT LegacyRenderWidgetHostHWND
                               NON_EXPORTED_BASE(ATL::CWindow),
                               ATL::CWinTraits<WS_CHILD> > {
  public:
+  virtual ~LegacyRenderWidgetHostHWND();
+
   DECLARE_WND_CLASS_EX(L"Chrome_RenderWidgetHostHWND", CS_DBLCLKS, 0);
 
   typedef ATL::CWindowImpl<LegacyRenderWidgetHostHWND,
@@ -60,10 +75,16 @@ class CONTENT_EXPORT LegacyRenderWidgetHostHWND
   // Creates and returns an instance of the LegacyRenderWidgetHostHWND class on
   // successful creation of a child window parented to the parent window passed
   // in.
-  static LegacyRenderWidgetHostHWND* Create(HWND parent);
+  static LegacyRenderWidgetHostHWND* Create(
+      HWND parent,
+      LegacyRenderWidgetHostHWNDDelegate* delegate);
 
-  // Destroys the HWND managed by this class.
-  void Destroy();
+  // Create an instance of LegacyRenderWidgetHostHWND purely for testing.
+  // Its parent is the desktop window and it always delegates to one
+  // BrowserAccessibilityManager. It deletes itself when the HWND is
+  // destroyed.
+  static LegacyRenderWidgetHostHWND* CreateForTesting(
+      BrowserAccessibilityManager* manager);
 
   BEGIN_MSG_MAP_EX(LegacyRenderWidgetHostHWND)
     MESSAGE_HANDLER_EX(WM_GETOBJECT, OnGetObject)
@@ -85,6 +106,8 @@ class CONTENT_EXPORT LegacyRenderWidgetHostHWND
     MESSAGE_HANDLER_EX(WM_SIZE, OnSize)
   END_MSG_MAP()
 
+  // May be deleted at any time by Windows! Other classes should never store
+  // this value.
   HWND hwnd() { return m_hWnd; }
 
   // Called when the child window is to be reparented to a new window.
@@ -94,13 +117,6 @@ class CONTENT_EXPORT LegacyRenderWidgetHostHWND
 
   IAccessible* window_accessible() { return window_accessible_; }
 
-  void set_browser_accessibility_manager(
-      content::BrowserAccessibilityManagerWin* manager) {
-    manager_ = manager;
-  }
-
-  void OnManagerDeleted(content::BrowserAccessibilityManagerWin* manager);
-
   // Functions to show and hide the window.
   void Show();
   void Hide();
@@ -108,18 +124,12 @@ class CONTENT_EXPORT LegacyRenderWidgetHostHWND
   // Resizes the window to the bounds passed in.
   void SetBounds(const gfx::Rect& bounds);
 
-  // The pointer to the containing RenderWidgetHostViewAura instance is passed
-  // here.
-  void set_host(RenderWidgetHostViewAura* host) {
-    host_ = host;
-  }
-
  protected:
   virtual void OnFinalMessage(HWND hwnd) OVERRIDE;
 
  private:
-  LegacyRenderWidgetHostHWND(HWND parent);
-  ~LegacyRenderWidgetHostHWND();
+  LegacyRenderWidgetHostHWND(HWND parent,
+                             LegacyRenderWidgetHostHWNDDelegate* delegate);
 
   bool Init();
 
@@ -145,18 +155,16 @@ class CONTENT_EXPORT LegacyRenderWidgetHostHWND
   LRESULT OnSize(UINT message, WPARAM w_param, LPARAM l_param);
   LRESULT OnSysCommand(UINT message, WPARAM w_param, LPARAM l_param);
 
-  content::BrowserAccessibilityManagerWin* manager_;
+  LegacyRenderWidgetHostHWNDDelegate* delegate_;
+  BrowserAccessibilityManager* manager_for_testing_;
   base::win::ScopedComPtr<IAccessible> window_accessible_;
 
   // Set to true if we turned on mouse tracking.
   bool mouse_tracking_enabled_;
 
-  RenderWidgetHostViewAura* host_;
-
   DISALLOW_COPY_AND_ASSIGN(LegacyRenderWidgetHostHWND);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_LEGACY_RENDER_WIDGET_HOST_WIN_H_
-