Metrics logging for user engagement of the Reload and Feedback buttons

ios/chrome/browser/ui/sad_tab/sad_tab_view.mm

 // Copyright 2015 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 "ios/chrome/browser/ui/sad_tab/sad_tab_view.h"
 
+#include "base/metrics/histogram_macros.h"
 #include "base/strings/sys_string_conversions.h"
 #include "components/grit/components_scaled_resources.h"
 #include "components/strings/grit/components_strings.h"
 #include "ios/chrome/browser/chrome_url_constants.h"
 #import "ios/chrome/browser/ui/colors/MDCPalette+CrAdditions.h"
 #import "ios/chrome/browser/ui/commands/UIKit+ChromeExecuteCommand.h"
 #import "ios/chrome/browser/ui/commands/ios_command_ids.h"
 #import "ios/chrome/browser/ui/commands/open_url_command.h"
 #include "ios/chrome/browser/ui/rtl_geometry.h"
 #import "ios/chrome/browser/ui/uikit_ui_util.h"
@@ skipping 93 matching lines @@
                         forLinkText:(nonnull NSString*)linkText;
 
 // The action selector for |_actionButton|.
 - (void)handleActionButtonTapped:(id)sender;
 
 // Returns the desired background color.
 + (UIColor*)sadTabBackgroundColor;
 
 @end
 
+// An enum for reporting interaction events to a UMA histogram. This
+// enumeration mimics that at sad_tab.cc
+typedef NS_ENUM(NSInteger, SadTabViewEvent) {

[PL, 2017/05/09 22:38:23]

This enumeration copies one reporting this metric for Desktop in sad_tab.cc.
I'd like to make both implementations use the same enumeration if possible.
If you agree, what would be the way to do this?:
a. File a bug for Desktop team to make their enum (and keys) public. Then adopt?
b. Place our own C++ enum somewhere accessible to both platforms and file a bug
for Desktop to adopt? If so, where?
c. Something else.

Thanks!

[Eugene But (OOO till 7-30), 2017/05/09 22:45:58]

I think it is C :). We should find a common place for this enum (perhaps in
components layer) and make changes for Desktop as well. isherman@ may help you
with finding a good place for the enum.

[PL, 2017/05/09 22:57:20]

Thanks! Reached out to isherman@ and sdy@ for discussion.

+  SadTabViewEventDisplayed = 0,
+  SadTabViewEventButtonClicked,
+  SadTabViewEventHelpLinkClicked,
+  SadTabViewEventMaxSadTabEvent,
+};
+
 #pragma mark - SadTabView
 
 @implementation SadTabView
 
 @synthesize imageView = _imageView;
 @synthesize containerView = _containerView;
 @synthesize titleLabel = _titleLabel;
 @synthesize messageLabel = _messageLabel;
 @synthesize footerLabel = _footerLabel;
 @synthesize footerLabelLinkController = _footerLabelLinkController;
@@ skipping 386 matching lines @@
   self.containerView.frame = AlignRectOriginAndSizeToPixels(
       CGRectMake(containerOriginX, containerOriginY, containerSize.width,
                  containerSize.height));
 }
 
 #pragma mark Util
 
 - (void)handleActionButtonTapped:(id)sender {
   switch (self.mode) {
     case SadTabViewMode::RELOAD:
+      UMA_HISTOGRAM_ENUMERATION("Tabs.SadTab.Reload.Event",
+                                SadTabViewEventButtonClicked,
+                                SadTabViewEventMaxSadTabEvent);
       self.navigationManager->Reload(web::ReloadType::NORMAL, true);
       break;
     case SadTabViewMode::FEEDBACK: {
+      UMA_HISTOGRAM_ENUMERATION("Tabs.SadTab.Feedback.Event",
+                                SadTabViewEventButtonClicked,
+                                SadTabViewEventMaxSadTabEvent);
       GenericChromeCommand* command =
           [[GenericChromeCommand alloc] initWithTag:IDC_REPORT_AN_ISSUE];
       [self chromeExecuteCommand:command];
       break;
     }
   };
 }
 
 + (UIColor*)sadTabBackgroundColor {
   return [UIColor colorWithWhite:kBackgroundColorBrightness alpha:1.0];
 }
 
 @end