Mac: Speculative fix for tracking area crashes

ui/base/cocoa/base_view.mm

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/base/cocoa/base_view.h"
 
 NSString* kViewDidBecomeFirstResponder =
     @"Chromium.kViewDidBecomeFirstResponder";
 NSString* kSelectionDirection = @"Chromium.kSelectionDirection";
 
-const int kTrackingOptions = NSTrackingMouseMoved |
-                             NSTrackingMouseEnteredAndExited |
-                             NSTrackingActiveAlways;
+@implementation BaseView
 
-@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.
 }
 
 - (EventHandled)keyEvent:(NSEvent*)theEvent {
   // The default implementation of this method does not handle any key events.
   // Derived classes should return kEventHandled if they handled an event,
   // otherwise it will be forwarded on to |super|.
   return kEventNotHandled;
 }
@@ skipping 96 matching lines @@
   new_rect.set_y(NSHeight([self bounds]) - new_rect.bottom());
   return new_rect;
 }
 
 - (NSRect)flipRectToNSRect:(gfx::Rect)rect {
   NSRect new_rect(NSRectFromCGRect(rect.ToCGRect()));
   new_rect.origin.y = NSHeight([self bounds]) - NSMaxY(new_rect);
   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