PrintPreview: Added new histograms for print preview.

chrome/browser/ui/webui/print_preview_handler.h

Index: chrome/browser/ui/webui/print_preview_handler.h
diff --git a/chrome/browser/ui/webui/print_preview_handler.h b/chrome/browser/ui/webui/print_preview_handler.h
index 6f4ac1dc082e3ccbe83ad1ac492513f14eba6282..0dcd42982b72940c58a043485c67cfec3dfb2954 100644
--- a/chrome/browser/ui/webui/print_preview_handler.h
+++ b/chrome/browser/ui/webui/print_preview_handler.h
@@ -85,6 +85,9 @@ class PrintPreviewHandler : public WebUIMessageHandler,
   // Helper function to activate the initiator tab and close the preview tab.
   void ActivateInitiatorTabAndClosePreviewTab();
 
+  // Adds all the recorded stats taken so far to histogram counts.
+  void ReportStats();
+
   // Pointer to current print system.
   scoped_refptr<printing::PrintBackend> print_backend_;
 
@@ -93,6 +96,16 @@ class PrintPreviewHandler : public WebUIMessageHandler,
 
   static FilePath* last_saved_path_;
 
+  // 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_;
+
+  // A count of how many times print preview failed.
+  int print_preview_failed_count_;
+
   DISALLOW_COPY_AND_ASSIGN(PrintPreviewHandler);
 };