Remove expired PrintPreview UMA collection code.

- PrintPreview.RegeneratePreviewRequest.BeforeFirstData:
  The UMA is not interesting.
- PrintPreview.ManagePrinters:
  https://crrev.com/518333 botched the data collection code, and
  https://crrev.com/613267 removed the method that should have
  collected the data.

Along the way, initialize more PrintPreviewHandler member variables in
the header.

Bug: 1041532
Change-Id: I319d87c17d11ee9191e9feba6351fe93f5aa44fb
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2135534Reviewed-by: Rebekah Potter <rbpotter@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>
Cr-Commit-Position: refs/heads/master@{#756388}

chrome/browser/ui/webui/print_preview/print_preview_handler.cc

@@ -522,18 +522,11 @@ class PrintPreviewHandler::AccessTokenService
 };
 #endif  // defined(OS_CHROMEOS)
 
-PrintPreviewHandler::PrintPreviewHandler()
-    : regenerate_preview_request_count_(0),
-      manage_printers_dialog_request_count_(0),
-      reported_failed_preview_(false),
-      has_logged_printers_count_(false),
-      identity_manager_(nullptr) {
+PrintPreviewHandler::PrintPreviewHandler() {
   ReportUserActionHistogram(PREVIEW_STARTED);
 }
 
 PrintPreviewHandler::~PrintPreviewHandler() {
-  base::UmaHistogramCounts1M("PrintPreview.ManagePrinters",
-                             manage_printers_dialog_request_count_);
   UnregisterForGaiaCookieChanges();
 }
 
@@ -1005,7 +998,6 @@ void PrintPreviewHandler::HandleGetAccessToken(const base::ListValue* args) {
 #if BUILDFLAG(ENABLE_BASIC_PRINT_DIALOG)
 void PrintPreviewHandler::HandleShowSystemDialog(
     const base::ListValue* /*args*/) {
-  manage_printers_dialog_request_count_++;
   ReportUserActionHistogram(FALLBACK_TO_ADVANCED_SETTINGS_DIALOG);
 
   WebContents* initiator = GetInitiator();

chrome/browser/ui/webui/print_preview/print_preview_handler.h

@@ -97,10 +97,6 @@ class PrintPreviewHandler : public content::WebUIMessageHandler,
                             int preview_uid,
                             int preview_request_id);
 
-  int regenerate_preview_request_count() const {
-    return regenerate_preview_request_count_;
-  }
-
   // Notifies PDF Printer Handler that |path| was selected. Used for tests.
   void FileSelectedForTesting(const base::FilePath& path,
                               int index,
@@ -314,16 +310,13 @@ class PrintPreviewHandler : public content::WebUIMessageHandler,
 
   // A count of how many requests received to regenerate preview data.
   // Initialized to 0 then incremented and emitted to a histogram.
-  int regenerate_preview_request_count_;
-
-  // A count of how many requests received to show manage printers dialog.
-  int manage_printers_dialog_request_count_;
+  int regenerate_preview_request_count_ = 0;
 
   // Whether we have already logged a failed print preview.
-  bool reported_failed_preview_;
+  bool reported_failed_preview_ = false;
 
   // Whether we have already logged the number of printers this session.
-  bool has_logged_printers_count_;
+  bool has_logged_printers_count_ = false;
 
   // Whether Google Cloud Print is enabled for the active profile.
   bool cloud_print_enabled_ = false;
@@ -338,7 +331,7 @@ class PrintPreviewHandler : public content::WebUIMessageHandler,
 
   // Pointer to the identity manager service so that print preview can listen
   // for GAIA cookie changes.
-  signin::IdentityManager* identity_manager_;
+  signin::IdentityManager* identity_manager_ = nullptr;
 
   // Handles requests for cloud printers. Created lazily by calling
   // GetPrinterHandler().

chrome/browser/ui/webui/print_preview/print_preview_ui.cc

@@ -675,9 +675,6 @@ void PrintPreviewUI::OnPreviewDataIsAvailable(
     base::UmaHistogramTimes(
         "PrintPreview.InitialDisplayTime",
         base::TimeTicks::Now() - initial_preview_start_time_);
-    base::UmaHistogramCounts1M(
-        "PrintPreview.RegeneratePreviewRequest.BeforeFirstData",
-        handler_->regenerate_preview_request_count());
     initial_preview_start_time_ = base::TimeTicks();
   }