MacViews: Implement Tab Dragging

chrome/browser/ui/views/tabs/window_finder_mac.mm

Index: chrome/browser/ui/views/tabs/window_finder_mac.mm
diff --git a/chrome/browser/ui/views/tabs/window_finder_mac.mm b/chrome/browser/ui/views/tabs/window_finder_mac.mm
index b2307da3550759fb0f79b3c117b8571fdc6fef0b..06e9843b5ac00fdb85faf557cb6538f43a09ce74 100644
--- a/chrome/browser/ui/views/tabs/window_finder_mac.mm
+++ b/chrome/browser/ui/views/tabs/window_finder_mac.mm
@@ -4,10 +4,34 @@
 
 #include "chrome/browser/ui/views/tabs/window_finder.h"
 
+#include <AppKit/AppKit.h>
+
+#include "ui/gfx/geometry/point.h"
+
 gfx::NativeWindow GetLocalProcessWindowAtPoint(
     chrome::HostDesktopType host_desktop_type,
     const gfx::Point& screen_point,
     const std::set<gfx::NativeWindow>& ignore) {
-  NOTIMPLEMENTED();
-  return NULL;
+
+  NSPoint ns_point = NSMakePoint(
+      screen_point.x(),
+      NSMaxY([[[NSScreen screens] objectAtIndex:0] frame]) - screen_point.y()
+  );
+
+  // Note [NSApp orderedWindows] doesn't include NSPanels.
+  for (NSWindow* window : [NSApp orderedWindows]) {
+    if (ignore.count(window))
+      continue;
+
+    if (![window isOnActiveSpace])
+      continue;
+
+    if (NSPointInRect(ns_point, [window frame])) {
+      NSLog(@"found: %@ at %@", window, NSStringFromPoint(ns_point));
+      return window;
+    }
+  }
+
+  NSLog(@"(nothing at %@)", NSStringFromPoint(ns_point));
+  return nil;
 }