[Mac] Refactor the logic of tab dragging out of TabView and into a new helper.

chrome/browser/ui/cocoa/tabs/tab_view.mm

Index: chrome/browser/ui/cocoa/tabs/tab_view.mm
diff --git a/chrome/browser/ui/cocoa/tabs/tab_view.mm b/chrome/browser/ui/cocoa/tabs/tab_view.mm
index 15d1fdbbb446b9164509ba0a55e6440501a0fa47..4cb230ccf80e75f247e7093a32ce514dbd9093a6 100644
--- a/chrome/browser/ui/cocoa/tabs/tab_view.mm
+++ b/chrome/browser/ui/cocoa/tabs/tab_view.mm
@@ -5,8 +5,6 @@
 #import "chrome/browser/ui/cocoa/tabs/tab_view.h"
 
 #include "base/logging.h"
-#import "base/mac/mac_util.h"
-#include "base/mac/scoped_cftyperef.h"
 #include "chrome/browser/themes/theme_service.h"
 #import "chrome/browser/ui/cocoa/nsview_additions.h"
 #import "chrome/browser/ui/cocoa/tabs/tab_controller.h"
@@ -39,9 +37,6 @@ const NSTimeInterval kAlertHideDuration = 0.4;
 // increasing/decreasing).
 const NSTimeInterval kGlowUpdateInterval = 0.025;
 
-const CGFloat kTearDistance = 36.0;
-const NSTimeInterval kTearDuration = 0.333;
-
 // This is used to judge whether the mouse has moved during rapid closure; if it
 // has moved less than the threshold, we want to close the tab.
 const CGFloat kRapidCloseDist = 2.5;
@@ -53,8 +48,6 @@ const CGFloat kRapidCloseDist = 2.5;
 - (void)resetLastGlowUpdateTime;
 - (NSTimeInterval)timeElapsedSinceLastGlowUpdate;
 - (void)adjustGlowValue;
-// TODO(davidben): When we stop supporting 10.5, this can be removed.
-- (int)getWorkspaceID:(NSWindow*)window useCache:(BOOL)useCache;
 - (NSBezierPath*)bezierPathForRect:(NSRect)rect;
 
 @end  // TabView(Private)
@@ -153,86 +146,7 @@ const CGFloat kRapidCloseDist = 2.5;
 
 // Returns |YES| if this tab can be torn away into a new window.
 - (BOOL)canBeDragged {
-  if ([self isClosing])
-    return NO;
-  NSWindowController* controller = [sourceWindow_ windowController];
-  if ([controller isKindOfClass:[TabWindowController class]]) {
-    TabWindowController* realController =
-        static_cast<TabWindowController*>(controller);
-    return [realController isTabDraggable:self];
-  }
-  return YES;
-}
-
-// Returns an array of controllers that could be a drop target, ordered front to
-// back. It has to be of the appropriate class, and visible (obviously). Note
-// that the window cannot be a target for itself.
-- (NSArray*)dropTargetsForController:(TabWindowController*)dragController {
-  NSMutableArray* targets = [NSMutableArray array];
-  NSWindow* dragWindow = [dragController window];
-  for (NSWindow* window in [NSApp orderedWindows]) {
-    if (window == dragWindow) continue;
-    if (![window isVisible]) continue;
-    // Skip windows on the wrong space.
-    if ([window respondsToSelector:@selector(isOnActiveSpace)]) {
-      if (![window performSelector:@selector(isOnActiveSpace)])
-        continue;
-    } else {
-      // TODO(davidben): When we stop supporting 10.5, this can be
-      // removed.
-      //
-      // We don't cache the workspace of |dragWindow| because it may
-      // move around spaces.
-      if ([self getWorkspaceID:dragWindow useCache:NO] !=
-          [self getWorkspaceID:window useCache:YES])
-        continue;
-    }
-    NSWindowController* controller = [window windowController];
-    if ([controller isKindOfClass:[TabWindowController class]]) {
-      TabWindowController* realController =
-          static_cast<TabWindowController*>(controller);
-      if ([realController canReceiveFrom:dragController])
-        [targets addObject:controller];
-    }
-  }
-  return targets;
-}
-
-// Call to clear out transient weak references we hold during drags.
-- (void)resetDragControllers {
-  draggedController_ = nil;
-  dragWindow_ = nil;
-  dragOverlay_ = nil;
-  sourceController_ = nil;
-  sourceWindow_ = nil;
-  targetController_ = nil;
-  workspaceIDCache_.clear();
-}
-
-// Sets whether the window background should be visible or invisible when
-// dragging a tab. The background should be invisible when the mouse is over a
-// potential drop target for the tab (the tab strip). It should be visible when
-// there's no drop target so the window looks more fully realized and ready to
-// become a stand-alone window.
-- (void)setWindowBackgroundVisibility:(BOOL)shouldBeVisible {
-  if (chromeIsVisible_ == shouldBeVisible)
-    return;
-
-  // There appears to be a race-condition in CoreAnimation where if we use
-  // animators to set the alpha values, we can't guarantee that we cancel them.
-  // This has the side effect of sometimes leaving the dragged window
-  // translucent or invisible. As a result, don't animate the alpha change.
-  [[draggedController_ overlayWindow] setAlphaValue:1.0];
-  if (targetController_) {
-    [dragWindow_ setAlphaValue:0.0];
-    [[draggedController_ overlayWindow] setHasShadow:YES];
-    [[targetController_ window] makeMainWindow];
-  } else {
-    [dragWindow_ setAlphaValue:0.5];
-    [[draggedController_ overlayWindow] setHasShadow:NO];
-    [[draggedController_ window] makeMainWindow];
-  }
-  chromeIsVisible_ = shouldBeVisible;
+  return [controller_ tabCanBeDragged:controller_];
 }
 
 // Handle clicks and drags in this button. We get here because we have
@@ -241,18 +155,20 @@ const CGFloat kRapidCloseDist = 2.5;
   if ([self isClosing])
     return;
 
-  NSPoint downLocation = [theEvent locationInWindow];
+  // Record the point at which this event happened. This is used by other mouse
+  // events that are dispatched from |-maybeStartDrag::|.
+  mouseDownPoint_ = [theEvent locationInWindow];
 
   // Record the state of the close button here, because selecting the tab will
   // unhide it.
-  BOOL closeButtonActive = [closeButton_ isHidden] ? NO : YES;
+  BOOL closeButtonActive = ![closeButton_ isHidden];
 
   // During the tab closure animation (in particular, during rapid tab closure),
   // we may get incorrectly hit with a mouse down. If it should have gone to the
   // close button, we send it there -- it should then track the mouse, so we
   // don't have to worry about mouse ups.
   if (closeButtonActive && [controller_ inRapidClosureMode]) {
-    NSPoint hitLocation = [[self superview] convertPoint:downLocation
+    NSPoint hitLocation = [[self superview] convertPoint:mouseDownPoint_
                                                 fromView:nil];
     if ([self hitTest:hitLocation] == closeButton_) {
       [closeButton_ mouseDown:theEvent];
@@ -260,376 +176,57 @@ const CGFloat kRapidCloseDist = 2.5;
     }
   }
 
-  [self resetDragControllers];
-
-  // Resolve overlay back to original window.
-  sourceWindow_ = [self window];
-  if ([sourceWindow_ isKindOfClass:[NSPanel class]]) {
-    sourceWindow_ = [sourceWindow_ parentWindow];
-  }
-
-  sourceWindowFrame_ = [sourceWindow_ frame];
-  sourceTabFrame_ = [self frame];
-  sourceController_ = [sourceWindow_ windowController];
-  tabWasDragged_ = NO;
-  tearTime_ = 0.0;
-  draggingWithinTabStrip_ = YES;
-  chromeIsVisible_ = NO;
-
-  // If there's more than one potential window to be a drop target, we want to
-  // treat a drag of a tab just like dragging around a tab that's already
-  // detached. Note that unit tests might have |-numberOfTabs| reporting zero
-  // since the model won't be fully hooked up. We need to be prepared for that
-  // and not send them into the "magnetic" codepath.
-  NSArray* targets = [self dropTargetsForController:sourceController_];
-  moveWindowOnDrag_ =
-      ([sourceController_ numberOfTabs] < 2 && ![targets count]) ||
-      ![self canBeDragged] ||
-      ![sourceController_ tabDraggingAllowed];
-  // If we are dragging a tab, a window with a single tab should immediately
-  // snap off and not drag within the tab strip.
-  if (!moveWindowOnDrag_)
-    draggingWithinTabStrip_ = [sourceController_ numberOfTabs] > 1;
-
-  dragOrigin_ = [NSEvent mouseLocation];
-
   // If the tab gets torn off, the tab controller will be removed from the tab
   // strip and then deallocated. This will also result in *us* being
   // deallocated. Both these are bad, so we prevent this by retaining the
   // controller.
   scoped_nsobject<TabController> controller([controller_ retain]);
 
-  // Because we move views between windows, we need to handle the event loop
-  // ourselves. Ideally we should use the standard event loop.
-  while (1) {
-    const NSUInteger mask =
-        NSLeftMouseUpMask | NSLeftMouseDraggedMask | NSKeyUpMask;
-    theEvent =
-        [NSApp nextEventMatchingMask:mask
-                           untilDate:[NSDate distantFuture]
-                              inMode:NSDefaultRunLoopMode dequeue:YES];
-    NSEventType type = [theEvent type];
-    if (type == NSKeyUp) {
-      if ([theEvent keyCode] == kVK_Escape) {
-        // Cancel the drag and restore the previous state.
-        if (draggingWithinTabStrip_) {
-          // Simply pretend the tab wasn't dragged (far enough).
-          tabWasDragged_ = NO;
-        } else {
-          [targetController_ removePlaceholder];
-          if ([sourceController_ numberOfTabs] < 2) {
-            // Revert to a single-tab window.
-            targetController_ = nil;
-          } else {
-            // Change the target to the source controller.
-            targetController_ = sourceController_;
-            [targetController_ insertPlaceholderForTab:self
-                                                 frame:sourceTabFrame_
-                                         yStretchiness:0];
-          }
-        }
-        // Call the |mouseUp:| code to end the drag.
-        [self mouseUp:theEvent];
-        break;
-      }
-    } else if (type == NSLeftMouseDragged) {
-      [self mouseDragged:theEvent];
-    } else if (type == NSLeftMouseUp) {
-      NSPoint upLocation = [theEvent locationInWindow];
-      CGFloat dx = upLocation.x - downLocation.x;
-      CGFloat dy = upLocation.y - downLocation.y;
-
-      // During rapid tab closure (mashing tab close buttons), we may get hit
-      // with a mouse down. As long as the mouse up is over the close button,
-      // and the mouse hasn't moved too much, we close the tab.
-      if (closeButtonActive &&
-          (dx*dx + dy*dy) <= kRapidCloseDist*kRapidCloseDist &&
-          [controller inRapidClosureMode]) {
-        NSPoint hitLocation =
-            [[self superview] convertPoint:[theEvent locationInWindow]
-                                  fromView:nil];
-        if ([self hitTest:hitLocation] == closeButton_) {
-          [controller closeTab:self];
-          break;
-        }
-      }
+  // Try to initiate a drag. This will spin a custom event loop and may
+  // dispatch other mouse events.
+  [controller_ maybeStartDrag:theEvent forTab:controller];
 
-      [self mouseUp:theEvent];
-      break;
-    } else {
-      // TODO(viettrungluu): [crbug.com/23830] We can receive right-mouse-ups
-      // (and maybe even others?) for reasons I don't understand. So we
-      // explicitly check for both events we're expecting, and log others. We
-      // should figure out what's going on.
-      LOG(WARNING) << "Spurious event received of type " << type << ".";
-    }
-  }
+  // The custom loop has ended, so clear the point.
+  mouseDownPoint_ = NSZeroPoint;
 }
 
 - (void)mouseDragged:(NSEvent*)theEvent {
-  // Special-case this to keep the logic below simpler.
-  if (moveWindowOnDrag_) {
-    if ([sourceController_ windowMovementAllowed]) {
-      NSPoint thisPoint = [NSEvent mouseLocation];
-      NSPoint origin = sourceWindowFrame_.origin;
-      origin.x += (thisPoint.x - dragOrigin_.x);
-      origin.y += (thisPoint.y - dragOrigin_.y);
-      [sourceWindow_ setFrameOrigin:NSMakePoint(origin.x, origin.y)];
-    }  // else do nothing.
-    return;
-  }
-
-  // First, go through the magnetic drag cycle. We break out of this if
-  // "stretchiness" ever exceeds a set amount.
-  tabWasDragged_ = YES;
-
-  if (draggingWithinTabStrip_) {
-    NSPoint thisPoint = [NSEvent mouseLocation];
-    CGFloat stretchiness = thisPoint.y - dragOrigin_.y;
-    stretchiness = copysign(sqrtf(fabs(stretchiness))/sqrtf(kTearDistance),
-                            stretchiness) / 2.0;
-    CGFloat offset = thisPoint.x - dragOrigin_.x;
-    if (fabsf(offset) > 100) stretchiness = 0;
-    [sourceController_ insertPlaceholderForTab:self
-                                         frame:NSOffsetRect(sourceTabFrame_,
-                                                            offset, 0)
-                                 yStretchiness:stretchiness];
-    // Check that we haven't pulled the tab too far to start a drag. This
-    // can include either pulling it too far down, or off the side of the tab
-    // strip that would cause it to no longer be fully visible.
-    BOOL stillVisible = [sourceController_ isTabFullyVisible:self];
-    CGFloat tearForce = fabs(thisPoint.y - dragOrigin_.y);
-    if ([sourceController_ tabTearingAllowed] &&
-        (tearForce > kTearDistance || !stillVisible)) {
-      draggingWithinTabStrip_ = NO;
-      // When you finally leave the strip, we treat that as the origin.
-      dragOrigin_.x = thisPoint.x;
-    } else {
-      // Still dragging within the tab strip, wait for the next drag event.
-      return;
-    }
-  }
-
-  // Do not start dragging until the user has "torn" the tab off by
-  // moving more than 3 pixels.
-  NSDate* targetDwellDate = nil;  // The date this target was first chosen.
-
-  NSPoint thisPoint = [NSEvent mouseLocation];
-
-  // Iterate over possible targets checking for the one the mouse is in.
-  // If the tab is just in the frame, bring the window forward to make it
-  // easier to drop something there. If it's in the tab strip, set the new
-  // target so that it pops into that window. We can't cache this because we
-  // need the z-order to be correct.
-  NSArray* targets = [self dropTargetsForController:draggedController_];
-  TabWindowController* newTarget = nil;
-  for (TabWindowController* target in targets) {
-    NSRect windowFrame = [[target window] frame];
-    if (NSPointInRect(thisPoint, windowFrame)) {
-      [[target window] orderFront:self];
-      NSRect tabStripFrame = [[target tabStripView] frame];
-      tabStripFrame.origin = [[target window]
-                              convertBaseToScreen:tabStripFrame.origin];
-      if (NSPointInRect(thisPoint, tabStripFrame)) {
-        newTarget = target;
-      }
-      break;
-    }
-  }
-
-  // If we're now targeting a new window, re-layout the tabs in the old
-  // target and reset how long we've been hovering over this new one.
-  if (targetController_ != newTarget) {
-    targetDwellDate = [NSDate date];
-    [targetController_ removePlaceholder];
-    targetController_ = newTarget;
-    if (!newTarget) {
-      tearTime_ = [NSDate timeIntervalSinceReferenceDate];
-      tearOrigin_ = [dragWindow_ frame].origin;
-    }
-  }
-
-  // Create or identify the dragged controller.
-  if (!draggedController_) {
-    // Get rid of any placeholder remaining in the original source window.
-    [sourceController_ removePlaceholder];
-
-    // Detach from the current window and put it in a new window. If there are
-    // no more tabs remaining after detaching, the source window is about to
-    // go away (it's been autoreleased) so we need to ensure we don't reference
-    // it any more. In that case the new controller becomes our source
-    // controller.
-    draggedController_ = [sourceController_ detachTabToNewWindow:self];
-    dragWindow_ = [draggedController_ window];
-    [dragWindow_ setAlphaValue:0.0];
-    if (![sourceController_ hasLiveTabs]) {
-      sourceController_ = draggedController_;
-      sourceWindow_ = dragWindow_;
-    }
-
-    // If dragging the tab only moves the current window, do not show overlay
-    // so that sheets stay on top of the window.
-    // Bring the target window to the front and make sure it has a border.
-    [dragWindow_ setLevel:NSFloatingWindowLevel];
-    [dragWindow_ setHasShadow:YES];
-    [dragWindow_ orderFront:nil];
-    [dragWindow_ makeMainWindow];
-    [draggedController_ showOverlay];
-    dragOverlay_ = [draggedController_ overlayWindow];
-    // Force the new tab button to be hidden. We'll reset it on mouse up.
-    [draggedController_ showNewTabButton:NO];
-    tearTime_ = [NSDate timeIntervalSinceReferenceDate];
-    tearOrigin_ = sourceWindowFrame_.origin;
-  }
-
-  // TODO(pinkerton): http://crbug.com/25682 demonstrates a way to get here by
-  // some weird circumstance that doesn't first go through mouseDown:. We
-  // really shouldn't go any farther.
-  if (!draggedController_ || !sourceController_)
-    return;
-
-  // When the user first tears off the window, we want slide the window to
-  // the current mouse location (to reduce the jarring appearance). We do this
-  // by calling ourselves back with additional mouseDragged calls (not actual
-  // events). |tearProgress| is a normalized measure of how far through this
-  // tear "animation" (of length kTearDuration) we are and has values [0..1].
-  // We use sqrt() so the animation is non-linear (slow down near the end
-  // point).
-  NSTimeInterval tearProgress =
-      [NSDate timeIntervalSinceReferenceDate] - tearTime_;
-  tearProgress /= kTearDuration;  // Normalize.
-  tearProgress = sqrtf(MAX(MIN(tearProgress, 1.0), 0.0));
-
-  // Move the dragged window to the right place on the screen.
-  NSPoint origin = sourceWindowFrame_.origin;
-  origin.x += (thisPoint.x - dragOrigin_.x);
-  origin.y += (thisPoint.y - dragOrigin_.y);
-
-  if (tearProgress < 1) {
-    // If the tear animation is not complete, call back to ourself with the
-    // same event to animate even if the mouse isn't moving. We need to make
-    // sure these get cancelled in mouseUp:.
-    [NSObject cancelPreviousPerformRequestsWithTarget:self];
-    [self performSelector:@selector(mouseDragged:)
-               withObject:theEvent
-               afterDelay:1.0f/30.0f];
-
-    // Set the current window origin based on how far we've progressed through
-    // the tear animation.
-    origin.x = (1 - tearProgress) * tearOrigin_.x + tearProgress * origin.x;
-    origin.y = (1 - tearProgress) * tearOrigin_.y + tearProgress * origin.y;
-  }
-
-  if (targetController_) {
-    // In order to "snap" two windows of different sizes together at their
-    // toolbar, we can't just use the origin of the target frame. We also have
-    // to take into consideration the difference in height.
-    NSRect targetFrame = [[targetController_ window] frame];
-    NSRect sourceFrame = [dragWindow_ frame];
-    origin.y = NSMinY(targetFrame) +
-                (NSHeight(targetFrame) - NSHeight(sourceFrame));
-  }
-  [dragWindow_ setFrameOrigin:NSMakePoint(origin.x, origin.y)];
-
-  // If we're not hovering over any window, make the window fully
-  // opaque. Otherwise, find where the tab might be dropped and insert
-  // a placeholder so it appears like it's part of that window.
-  if (targetController_) {
-    if (![[targetController_ window] isKeyWindow]) {
-      // && ([targetDwellDate timeIntervalSinceNow] < -REQUIRED_DWELL)) {
-      [[targetController_ window] orderFront:nil];
-      targetDwellDate = nil;
-    }
-
-    // Compute where placeholder should go and insert it into the
-    // destination tab strip.
-    TabView* draggedTabView = (TabView*)[draggedController_ activeTabView];
-    NSRect tabFrame = [draggedTabView frame];
-    tabFrame.origin = [dragWindow_ convertBaseToScreen:tabFrame.origin];
-    tabFrame.origin = [[targetController_ window]
-                        convertScreenToBase:tabFrame.origin];
-    tabFrame = [[targetController_ tabStripView]
-                convertRect:tabFrame fromView:nil];
-    [targetController_ insertPlaceholderForTab:self
-                                         frame:tabFrame
-                                 yStretchiness:0];
-    [targetController_ layoutTabs];
-  } else {
-    [dragWindow_ makeKeyAndOrderFront:nil];
-  }
-
-  // Adjust the visibility of the window background. If there is a drop target,
-  // we want to hide the window background so the tab stands out for
-  // positioning. If not, we want to show it so it looks like a new window will
-  // be realized.
-  BOOL chromeShouldBeVisible = targetController_ == nil;
-  [self setWindowBackgroundVisibility:chromeShouldBeVisible];
+  [controller_ continueDrag:theEvent];
 }
 
 - (void)mouseUp:(NSEvent*)theEvent {
-  // The drag/click is done. If the user dragged the mouse, finalize the drag
-  // and clean up.
-
   // Fire the action to select the tab.
   if ([[controller_ target] respondsToSelector:[controller_ action]])
     [[controller_ target] performSelector:[controller_ action]
                                withObject:self];
 
-  // Special-case this to keep the logic below simpler.
-  if (moveWindowOnDrag_)
-    return;
-
-  // Cancel any delayed -mouseDragged: requests that may still be pending.
-  [NSObject cancelPreviousPerformRequestsWithTarget:self];
-
-  // TODO(pinkerton): http://crbug.com/25682 demonstrates a way to get here by
-  // some weird circumstance that doesn't first go through mouseDown:. We
-  // really shouldn't go any farther.
-  if (!sourceController_)
-    return;
-
-  // We are now free to re-display the new tab button in the window we're
-  // dragging. It will show when the next call to -layoutTabs (which happens
-  // indrectly by several of the calls below, such as removing the placeholder).
-  [draggedController_ showNewTabButton:YES];
-
-  if (draggingWithinTabStrip_) {
-    if (tabWasDragged_) {
-      // Move tab to new location.
-      DCHECK([sourceController_ numberOfTabs]);
-      TabWindowController* dropController = sourceController_;
-      [dropController moveTabView:[dropController activeTabView]
-                   fromController:nil];
-    }
-  } else if (targetController_) {
-    // Move between windows. If |targetController_| is nil, we're not dropping
-    // into any existing window.
-    NSView* draggedTabView = [draggedController_ activeTabView];
-    [targetController_ moveTabView:draggedTabView
-                    fromController:draggedController_];
-    // Force redraw to avoid flashes of old content before returning to event
-    // loop.
-    [[targetController_ window] display];
-    [targetController_ showWindow:nil];
-    [draggedController_ removeOverlay];
-  } else {
-    // Only move the window around on screen. Make sure it's set back to
-    // normal state (fully opaque, has shadow, has key, etc).
-    [draggedController_ removeOverlay];
-    // Don't want to re-show the window if it was closed during the drag.
-    if ([dragWindow_ isVisible]) {
-      [dragWindow_ setAlphaValue:1.0];
-      [dragOverlay_ setHasShadow:NO];
-      [dragWindow_ setHasShadow:YES];
-      [dragWindow_ makeKeyAndOrderFront:nil];
+  // Check for rapid tab closure.
+  if ([theEvent type] == NSLeftMouseUp) {
+    NSPoint upLocation = [theEvent locationInWindow];
+    CGFloat dx = upLocation.x - mouseDownPoint_.x;
+    CGFloat dy = upLocation.y - mouseDownPoint_.y;
+
+    // During rapid tab closure (mashing tab close buttons), we may get hit
+    // with a mouse down. As long as the mouse up is over the close button,
+    // and the mouse hasn't moved too much, we close the tab.
+    if (![closeButton_ isHidden] &&
+        (dx*dx + dy*dy) <= kRapidCloseDist*kRapidCloseDist &&
+        [controller_ inRapidClosureMode]) {
+      NSPoint hitLocation =
+          [[self superview] convertPoint:[theEvent locationInWindow]
+                                fromView:nil];
+      if ([self hitTest:hitLocation] == closeButton_) {
+        [controller_ closeTab:self];
+      }
     }
-    [[draggedController_ window] setLevel:NSNormalWindowLevel];
-    [draggedController_ removePlaceholder];
   }
-  [sourceController_ removePlaceholder];
-  chromeIsVisible_ = YES;
 
-  [self resetDragControllers];
+  // Messaging the drag controller with |-endDrag:| would seem like the right
+  // thing to do here. But, when a tab has been detached, the controller's
+  // target is nil until the drag is finalized. Since |-mouseUp:| gets called
+  // via the manual event loop inside -[TabStripDragController
+  // maybeStartDrag:forTab:], the drag controller can end the dragging session
+  // itself directly after calling this.
 }
 
 - (void)otherMouseUp:(NSEvent*)theEvent {
@@ -972,54 +569,6 @@ const CGFloat kRapidCloseDist = 2.5;
   [self setNeedsDisplay:YES];
 }
 
-// Returns the workspace id of |window|. If |useCache|, then lookup
-// and remember the value in |workspaceIDCache_| until the end of the
-// current drag.
-- (int)getWorkspaceID:(NSWindow*)window useCache:(BOOL)useCache {
-  CGWindowID windowID = [window windowNumber];
-  if (useCache) {
-    std::map<CGWindowID, int>::iterator iter =
-        workspaceIDCache_.find(windowID);
-    if (iter != workspaceIDCache_.end())
-      return iter->second;
-  }
-
-  int workspace = -1;
-  // It's possible to query in bulk, but probably not necessary.
-  base::mac::ScopedCFTypeRef<CFArrayRef> windowIDs(CFArrayCreate(
-      NULL, reinterpret_cast<const void **>(&windowID), 1, NULL));
-  base::mac::ScopedCFTypeRef<CFArrayRef> descriptions(
-      CGWindowListCreateDescriptionFromArray(windowIDs));
-  DCHECK(CFArrayGetCount(descriptions.get()) <= 1);
-  if (CFArrayGetCount(descriptions.get()) > 0) {
-    CFDictionaryRef dict = static_cast<CFDictionaryRef>(
-        CFArrayGetValueAtIndex(descriptions.get(), 0));
-    DCHECK(CFGetTypeID(dict) == CFDictionaryGetTypeID());
-
-    // Sanity check the ID.
-    CFNumberRef otherIDRef = (CFNumberRef)base::mac::GetValueFromDictionary(
-        dict, kCGWindowNumber, CFNumberGetTypeID());
-    CGWindowID otherID;
-    if (otherIDRef &&
-        CFNumberGetValue(otherIDRef, kCGWindowIDCFNumberType, &otherID) &&
-        otherID == windowID) {
-      // And then get the workspace.
-      CFNumberRef workspaceRef = (CFNumberRef)base::mac::GetValueFromDictionary(
-          dict, kCGWindowWorkspace, CFNumberGetTypeID());
-      if (!workspaceRef ||
-          !CFNumberGetValue(workspaceRef, kCFNumberIntType, &workspace)) {
-        workspace = -1;
-      }
-    } else {
-      NOTREACHED();
-    }
-  }
-  if (useCache) {
-    workspaceIDCache_[windowID] = workspace;
-  }
-  return workspace;
-}
-
 // Returns the bezier path used to draw the tab given the bounds to draw it in.
 - (NSBezierPath*)bezierPathForRect:(NSRect)rect {
   const CGFloat lineWidth = [self cr_lineWidth];