Mac: fix Esc-key cancellation of bookmark bar button drags.

chrome/browser/cocoa/bookmark_button.mm

 // Copyright (c) 2009 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 "base/logging.h"
 #import "base/scoped_nsobject.h"
 #import "chrome/browser/cocoa/bookmark_button.h"
 #import "chrome/browser/cocoa/bookmark_button_cell.h"
 #import "third_party/GTM/AppKit/GTMTheme.h"
 
@@ skipping 28 matching lines @@
   }
   return self;
 }
 
 // By default, NSButton ignores middle-clicks.
 - (void)otherMouseUp:(NSEvent*)event {
   [self performClick:self];
 }
 
 - (void)beginDrag:(NSEvent*)event {
+  // Starting drag. Never start another drag until another mouse down.
+  mayDragStart_ = NO;
+
   NSSize dragOffset = NSMakeSize(0.0, 0.0);
   NSPasteboard* pboard = [NSPasteboard pasteboardWithName:NSDragPboard];
   [pboard declareTypes:[NSArray arrayWithObject:kBookmarkButtonDragType]
                  owner:self];
 
   // This NSData is no longer referenced once the function ends so
   // there is no need to retain/release when placing in here as an
   // opaque pointer.
   [pboard setData:[NSData dataWithBytes:&self length:sizeof(self)]
           forType:kBookmarkButtonDragType];
@@ skipping 16 matching lines @@
            operation:(NSDragOperation)operation {
   beingDragged_ = NO;
   [[self cell] setHighlighted:NO];
 }
 
 - (NSDragOperation)draggingSourceOperationMaskForLocal:(BOOL)isLocal {
   return isLocal ? NSDragOperationMove : NSDragOperationNone;
 }
 
 - (void)mouseUp:(NSEvent*)theEvent {
+  // Make sure that we can't start a drag until we see a mouse down again.
+  mayDragStart_ = NO;
+
   // This conditional is never true (DnD loops in Cocoa eat the mouse
   // up) but I added it in case future versions of Cocoa do unexpected
   // things.
-  if (beingDragged_)
+  if (beingDragged_) {
+    NOTREACHED();
     return [super mouseUp:theEvent];
+  }
 
   // There are non-drag cases where a mouseUp: may happen
   // (e.g. mouse-down, cmd-tab to another application, move mouse,
   // mouse-up).  So we check.
   NSPoint viewLocal = [self convertPoint:[theEvent locationInWindow]
                                 fromView:[[self window] contentView]];
   if (NSPointInRect(viewLocal, [self bounds])) {
     [self performClick:self];
   } else {
     [[self cell] setHighlighted:NO];
   }
 }
 
 // Mimic "begin a click" operation visually.  Do NOT follow through
 // with normal button event handling.
 - (void)mouseDown:(NSEvent*)theEvent {
+  mayDragStart_ = YES;
   [[self cell] setHighlighted:YES];
   initialMouseDownLocation_ = [theEvent locationInWindow];
 }
 
 // Return YES if we have crossed a threshold of movement after
 // mouse-down when we should begin a drag.  Else NO.
 - (BOOL)hasCrossedDragThreshold:(NSEvent*)theEvent {
   NSPoint currentLocation = [theEvent locationInWindow];
   if ((abs(currentLocation.x - initialMouseDownLocation_.x) >
        kWebDragStartHysteresisX) ||
       (abs(currentLocation.y - initialMouseDownLocation_.y) >
        kWebDragStartHysteresisY)) {
     return YES;
   } else {
     return NO;
   }
 }
 
 - (void)mouseDragged:(NSEvent*)theEvent {
-  if (beingDragged_)
+  if (beingDragged_) {
     [super mouseDragged:theEvent];
-  else {
-    if (draggable_ && [self hasCrossedDragThreshold:theEvent]) {
-      [self beginDrag:theEvent];
-    }
+  } else if (draggable_ && mayDragStart_ &&
+             [self hasCrossedDragThreshold:theEvent]) {
+    [self beginDrag:theEvent];
   }
 }
 
 @end
 
 @implementation BookmarkButton(Private)
 
 - (NSImage*)dragImage {
   NSRect bounds = [self bounds];
 
@@ skipping 21 matching lines @@
   [image drawAtPoint:NSMakePoint(0, 0)
             fromRect:NSMakeRect(0, 0, NSWidth(bounds), NSHeight(bounds))
            operation:NSCompositeSourceOver
             fraction:kDragImageOpacity];
 
   [dragImage unlockFocus];
   return dragImage;
 }
 
 @end  // @implementation BookmarkButton(Private)