Allow Source<T> and Details<T> to be instantiated with T = const Foo.

Review URL: http://codereview.chromium.org/118185

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@17550 0039d316-1c4b-4281-b951-d872f2087c98

4 files changed, 19 insertions, 28 deletions

diff --git a/chrome/browser/automation/automation_window_tracker.h b/chrome/browser/automation/automation_window_tracker.h
index a4e505a..53a48aa2 100644
--- a/chrome/browser/automation/automation_window_tracker.h
+++ b/chrome/browser/automation/automation_window_tracker.h
@@ -8,26 +8,7 @@
 #include "base/gfx/native_widget_types.h"
 #include "build/build_config.h"
 #include "chrome/browser/automation/automation_resource_tracker.h"
-
-#if defined(OS_WIN)
-// Since HWNDs aren't pointers, we can't have NativeWindow
-// be directly a pointer and so must explicitly declare the Source types
-// for it.
 #include "chrome/common/native_window_notification_source.h"
-#elif defined(OS_LINUX) || defined(OS_MACOSX)
-// But on Linux and Mac, it is a pointer so this definition suffices.
-template<>
-class Source<gfx::NativeWindow> : public NotificationSource {
- public:
-  explicit Source(gfx::NativeWindow win) : NotificationSource(win) {}
-
-  explicit Source(const NotificationSource& other)
-      : NotificationSource(other) {}
-
-  gfx::NativeWindow operator->() const { return ptr(); }
-  gfx::NativeWindow ptr() const { return static_cast<gfx::NativeWindow>(ptr_); }
-};
-#endif
 
 class AutomationWindowTracker
     : public AutomationResourceTracker<gfx::NativeWindow> {
diff --git a/chrome/common/native_window_notification_source.h b/chrome/common/native_window_notification_source.h
index 3db7e50..1cb270d 100644
--- a/chrome/common/native_window_notification_source.h
+++ b/chrome/common/native_window_notification_source.h
@@ -8,8 +8,10 @@
 #include "base/gfx/native_widget_types.h"
 #include "chrome/common/notification_source.h"
 
-// Specialization of the Source class for HWND.  This is needed as the Source
-// class expects a pointer type.
+// Specialization of the Source class for native windows.  On Windows, these are
+// HWNDs rather than pointers, and since the Source class expects a pointer
+// type, this is necessary.  On Mac/Linux, these are pointers, so this is
+// unnecessary but harmless.
 template<>
 class Source<gfx::NativeWindow> : public NotificationSource {
  public:
@@ -19,7 +21,9 @@ class Source<gfx::NativeWindow> : public NotificationSource {
       : NotificationSource(other) {}
 
   gfx::NativeWindow operator->() const { return ptr(); }
-  gfx::NativeWindow ptr() const { return static_cast<gfx::NativeWindow>(ptr_); }
+  gfx::NativeWindow ptr() const {
+    return static_cast<gfx::NativeWindow>(const_cast<void*>(ptr_));
+  }
 };
 
 #endif  // CHROME_COMMON_NATIVE_WINDOW_NOTIFICATION_SOURCE_H_
diff --git a/chrome/common/notification_details.h b/chrome/common/notification_details.h
index c938542..ee10111 100644
--- a/chrome/common/notification_details.h
+++ b/chrome/common/notification_details.h
@@ -33,9 +33,11 @@ class NotificationDetails {
   }
 
  protected:
-  NotificationDetails(void* ptr) : ptr_(ptr) {}
+  NotificationDetails(const void* ptr) : ptr_(ptr) {}
 
-  void* ptr_;
+  // Declaring this const allows Details<T> to be used with both T = Foo and
+  // T = const Foo.
+  const void* ptr_;
 };
 
 template <class T>
@@ -46,7 +48,8 @@ class Details : public NotificationDetails {
     : NotificationDetails(other) {}
 
   T* operator->() const { return ptr(); }
-  T* ptr() const { return static_cast<T*>(ptr_); }
+  // The casts here allow this to compile with both T = Foo and T = const Foo.
+  T* ptr() const { return static_cast<T*>(const_cast<void*>(ptr_)); }
 };
 
 #endif  // CHROME_COMMON_NOTIFICATION_DETAILS_H__
diff --git a/chrome/common/notification_source.h b/chrome/common/notification_source.h
index 93b20ba..fb37124 100644
--- a/chrome/common/notification_source.h
+++ b/chrome/common/notification_source.h
@@ -31,9 +31,11 @@ class NotificationSource {
   }
 
  protected:
-  NotificationSource(void* ptr) : ptr_(ptr) {}
+  NotificationSource(const void* ptr) : ptr_(ptr) {}
 
-  void* ptr_;
+  // Declaring this const allows Source<T> to be used with both T = Foo and
+  // T = const Foo.
+  const void* ptr_;
 };
 
 template <class T>
@@ -45,7 +47,8 @@ class Source : public NotificationSource {
     : NotificationSource(other) {}
 
   T* operator->() const { return ptr(); }
-  T* ptr() const { return static_cast<T*>(ptr_); }
+  // The casts here allow this to compile with both T = Foo and T = const Foo.
+  T* ptr() const { return static_cast<T*>(const_cast<void*>(ptr_)); }
 };
 
 #endif  // CHROME_COMMON_NOTIFICATION_SOURCE_H__