mac: Fix sending of mouse moved events after resizing window's lower left corner

ui/base/cocoa/base_view.mm

Index: ui/base/cocoa/base_view.mm
diff --git a/ui/base/cocoa/base_view.mm b/ui/base/cocoa/base_view.mm
index d5f89e89aadf8570a0872d8c3ae80d11a3d447a7..a40c2415f83354665e22188e823e364ac3fca67e 100644
--- a/ui/base/cocoa/base_view.mm
+++ b/ui/base/cocoa/base_view.mm
@@ -8,19 +8,19 @@ NSString* kViewDidBecomeFirstResponder =
     @"Chromium.kViewDidBecomeFirstResponder";
 NSString* kSelectionDirection = @"Chromium.kSelectionDirection";
 
+const int kTrackingOptions = NSTrackingMouseMoved |
+                             NSTrackingMouseEnteredAndExited |
+                             NSTrackingActiveAlways;
+
 @implementation BaseView
 
 - (id)initWithFrame:(NSRect)frame {
   self = [super initWithFrame:frame];
   if (self) {
-    trackingArea_ =
-        [[NSTrackingArea alloc] initWithRect:frame
-                                     options:NSTrackingMouseMoved |
-                                             NSTrackingMouseEnteredAndExited |
-                                             NSTrackingActiveInActiveApp |
-                                             NSTrackingInVisibleRect
-                                       owner:self
-                                    userInfo:nil];
+    trackingArea_ = [[NSTrackingArea alloc] initWithRect:frame

[Alexei Svitkine (slow), 2013/03/14 00:42:47]

Could this just call [self refreshTrackingAreaSize], or does [self
removeTrackingArea:nil] cause problems?

+                                                 options:kTrackingOptions
+                                                   owner:self
+                                                userInfo:nil];
     [self addTrackingArea:trackingArea_];
   }
   return self;
@@ -143,4 +143,31 @@ NSString* kSelectionDirection = @"Chromium.kSelectionDirection";
   return new_rect;
 }
 
+- (void)refreshTrackingAreaSize {

[Alexei Svitkine (slow), 2013/03/14 00:42:47]

Should this be called refreshTrackingAreaRect, since it's not just the size
you're interested in, right?

+  // NSTrackingInVisibleRect doesn't work correctly with Lion's window resizing,
+  // http://crbug.com/176725 /  http://openradar.appspot.com/radar?id=2773401 .
+  // Tear down old tracking area and create a new one as workaround.
+  [self removeTrackingArea:trackingArea_];
+  [trackingArea_ release];
+  trackingArea_ = [[NSTrackingArea alloc] initWithRect:[self frame]
+                                               options:kTrackingOptions
+                                                 owner:self
+                                              userInfo:nil];
+  [self addTrackingArea:trackingArea_];
+}
+
+- (void)setFrame:(NSRect)newRect {
+  BOOL sizeChanged = !NSEqualSizes([self frame].size, newRect.size);
+  [super setFrame:newRect];
+
+  // NB: -[NSView setFrame:] calls through -setFrameSize:.
+  if (!sizeChanged)
+    [self refreshTrackingAreaSize];

[Alexei Svitkine (slow), 2013/03/14 00:42:47]

So this is called because -[NSView setFrame:] doesn't call -setFrameSize: if the
size hasn't changed? Maybe clarify this in the comment ("if the size changed").

It would also be nice to at-least have a test for what you say in the comment
(that setFrame: does call setFrameSize:), to make sure we don't break if the
implementation of -setFrame: changes.

+}
+
+- (void)setFrameSize:(NSSize)newSize {
+  [super setFrameSize:newSize];
+  [self refreshTrackingAreaSize];
+}
+
 @end