Mac: Speculative fix for tracking area crashes

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 b37b6789435d8a6da2698e72d63b1779adba2957..24dba8cb7c1e07875c9e91287dcfd483c66b91e5 100644
--- a/ui/base/cocoa/base_view.mm
+++ b/ui/base/cocoa/base_view.mm
@@ -8,20 +8,82 @@ NSString* kViewDidBecomeFirstResponder =
     @"Chromium.kViewDidBecomeFirstResponder";
 NSString* kSelectionDirection = @"Chromium.kSelectionDirection";
 
-const int kTrackingOptions = NSTrackingMouseMoved |
-                             NSTrackingMouseEnteredAndExited |
-                             NSTrackingActiveAlways;
-
 @implementation BaseView
 
+- (instancetype)initWithFrame:(NSRect)frame useEventTap:(BOOL)useEventTap {
+  if ((self = [super initWithFrame:frame])) {
+    [self initBaseViewUsingEventTap:YES];
+  }
+  return self;
+}
+
+- (instancetype)initWithFrame:(NSRect)frame {
+  if ((self = [super initWithFrame:frame])) {
+    [self initBaseViewUsingEventTap:NO];
+  }
+  return self;
+}
+
+- (instancetype)initWithCoder:(NSCoder*)decoder {
+  if ((self = [super initWithCoder:decoder])) {
+    [self initBaseViewUsingEventTap:NO];
+  }
+  return self;
+}
+
+- (void)initBaseViewUsingEventTap:(BOOL)useEventTap {
+  NSTrackingAreaOptions trackingOptions = NSTrackingMouseEnteredAndExited |
+                                          NSTrackingActiveAlways |
+                                          NSTrackingInVisibleRect;
+  if (!useEventTap)
+    trackingOptions |= NSTrackingMouseMoved;
+  trackingArea_.reset([[CrTrackingArea alloc] initWithRect:NSZeroRect
+                                                   options:trackingOptions
+                                                     owner:self
+                                                  userInfo:nil]);
+  [self addTrackingArea:trackingArea_.get()];
+
+  if (useEventTap) {
+    // Workaround for http://crbug.com/176725
+    // Check if the mouse moved over us.
+    // Don't do it if we are firstResponder to avoid processing the event twice.
+    eventTap_ = [NSEvent addLocalMonitorForEventsMatchingMask:NSMouseMovedMask
+        handler:^NSEvent*(NSEvent* event) {
+            NSWindow* window = [self window];
+            if (window && window == [event window] &&
+                [window firstResponder] != self) {
+              NSPoint location =
+                  [[self superview] convertPoint:[event locationInWindow]
+                                        fromView:nil];
+              if ([self hitTest:location])
+                [self mouseMoved:event];
+            }
+            return event;
+        }];
+  }
+}
+
 - (void)dealloc {
   if (trackingArea_.get())
     [self removeTrackingArea:trackingArea_.get()];
   trackingArea_.reset(nil);
 
+  if (eventTap_)
+    [NSEvent removeMonitor:eventTap_];
+
   [super dealloc];
 }
 
+- (void)viewDidMoveToWindow {
+  [super viewDidMoveToWindow];
+
+  // Ensure our event tap gets mouse moved events. The mouse moved events are
+  // normally sent to the window's firstResponder (like key events, unlike
+  // other mouse events).
+  if (eventTap_)
+    [[self window] setAcceptsMouseMovedEvents:YES];

[Nico, 2015/02/26 22:16:07]

Does this have to be called with NO at some point?

[Andre, 2015/02/26 22:29:58]

We might if this view is removed from the window, but there likely are still
views that wants this as YES,
such as RWHVCocoa of another tab. Seems like it should be safe to leave it set,
in practice a browser
window will always have this set because it always has an active RWHVCocoa.

+}
+
 - (void)mouseEvent:(NSEvent*)theEvent {
   // This method left intentionally blank.
 }
@@ -138,19 +200,4 @@ const int kTrackingOptions = NSTrackingMouseMoved |
   return new_rect;
 }
 
-- (void)updateTrackingAreas {
-  [super updateTrackingAreas];
-
-  // 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.
-  if (trackingArea_.get())
-    [self removeTrackingArea:trackingArea_.get()];
-  trackingArea_.reset([[CrTrackingArea alloc] initWithRect:[self bounds]
-                                                   options:kTrackingOptions
-                                                     owner:self
-                                                  userInfo:nil]);
-  [self addTrackingArea:trackingArea_.get()];
-}
-
 @end