[Mac] Confirm-to-quit: Add histogram metrics.

chrome/browser/ui/cocoa/confirm_quit_panel_controller.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.
 
 #import <Cocoa/Cocoa.h>
 #import <QuartzCore/QuartzCore.h>
 
 #include "base/logging.h"
 #include "base/memory/scoped_nsobject.h"
+#include "base/metrics/histogram.h"
 #include "base/sys_string_conversions.h"
 #import "chrome/browser/ui/cocoa/confirm_quit_panel_controller.h"
 #include "grit/generated_resources.h"
 #include "ui/base/l10n/l10n_util_mac.h"
 
 // Constants ///////////////////////////////////////////////////////////////////
 
 // How long the user must hold down Cmd+Q to confirm the quit.
 const NSTimeInterval kTimeToConfirmQuit = 1.5;
 
 // Leeway between the |targetDate| and the current time that will confirm a
 // quit.
 const NSTimeInterval kTimeDeltaFuzzFactor = 1.0;
 
 // Duration of the window fade out animation.
 const NSTimeInterval kWindowFadeAnimationDuration = 0.2;
 
+// For metrics recording only: How long the user must hold the keys to
+// differentitate kDoubleTap from kTapHold.
+const NSTimeInterval kDoubleTapTimeDelta = 0.32;
+
+// Functions ///////////////////////////////////////////////////////////////////
+
+namespace confirm_quit {
+
+void RecordHistogram(ConfirmQuitMetric sample) {
+  HISTOGRAM_ENUMERATION("ConfirmToQuit", sample, kSampleCount);
+}
+
+}  // namespace confirm_quit
+
 // Custom Content View /////////////////////////////////////////////////////////
 
 // The content view of the window that draws a custom frame.
 @interface ConfirmQuitFrameView : NSView {
  @private
   NSTextField* message_;  // Weak, owned by the view hierarchy.
 }
 - (void)setMessageText:(NSString*)text;
 @end
 
@@ skipping 173 matching lines @@
     // tap Cmd+Q and then hold it with the window still open, this double-tap
     // logic will run and cause the quit to get committed. If the key
     // combination held down, the system will start sending the Cmd+Q event to
     // the next key application, and so on. This is bad, so instead we hide all
     // the windows (without animation) to look like we've "quit" and then wait
     // for the KeyUp event to commit the quit.
     [self hideAllWindowsForApplication:app withDuration:0];
     NSEvent* nextEvent = [self pumpEventQueueForKeyUp:app
                                             untilDate:[NSDate distantFuture]];
     [app discardEventsMatchingMask:NSAnyEventMask beforeEvent:nextEvent];
+
+    // Based on how long the user held the keys, record the metric.
+    if ([[NSDate date] timeIntervalSinceDate:timeNow] < kDoubleTapTimeDelta)
+      confirm_quit::RecordHistogram(confirm_quit::kDoubleTap);
+    else
+      confirm_quit::RecordHistogram(confirm_quit::kTapHold);
     return NSTerminateNow;
   } else {
     [lastQuitAttempt release];  // Harmless if already nil.
     lastQuitAttempt = [timeNow retain];  // Record this attempt for next time.
   }
 
   // Show the info panel that explains what the user must to do confirm quit.
   [self showWindow:self];
 
   // Spin a nested run loop until the |targetDate| is reached or a KeyUp event
@@ skipping 26 matching lines @@
     }
   } while (!nextEvent);
 
   // The user has released the key combo. Discard any events (i.e. the
   // repeated KeyDown Cmd+Q).
   [app discardEventsMatchingMask:NSAnyEventMask beforeEvent:nextEvent];
 
   if (willQuit) {
     // The user held down the combination long enough that quitting should
     // happen.
+    confirm_quit::RecordHistogram(confirm_quit::kHoldDuration);
     return NSTerminateNow;
   } else {
     // Slowly fade the confirm window out in case the user doesn't
     // understand what they have to do to quit.
     [self dismissPanel];
     return NSTerminateCancel;
   }
 
   // Default case: terminate.
   return NSTerminateNow;
@@ skipping 95 matching lines @@
   if (modifiers & NSAlternateKeyMask)
     [string appendString:@"\u2325"];
   if (modifiers & NSShiftKeyMask)
     [string appendString:@"\u21E7"];
 
   [string appendString:[item.characters() uppercaseString]];
   return string;
 }
 
 @end