Adding UMA stats for dragdrop events for both touch and mouse.

ui/views/widget/desktop_aura/desktop_drag_drop_client_aurax11.cc

Index: ui/views/widget/desktop_aura/desktop_drag_drop_client_aurax11.cc
diff --git a/ui/views/widget/desktop_aura/desktop_drag_drop_client_aurax11.cc b/ui/views/widget/desktop_aura/desktop_drag_drop_client_aurax11.cc
index 8a56b8de9689f8132adc9f2190b3154f4dced4b0..49448203374729953e0630c7da9f6be50a45ccae 100644
--- a/ui/views/widget/desktop_aura/desktop_drag_drop_client_aurax11.cc
+++ b/ui/views/widget/desktop_aura/desktop_drag_drop_client_aurax11.cc
@@ -9,6 +9,7 @@
 #include "base/event_types.h"
 #include "base/lazy_instance.h"
 #include "base/message_loop/message_loop.h"
+#include "base/metrics/histogram_macros.h"
 #include "third_party/skia/include/core/SkBitmap.h"
 #include "ui/aura/client/capture_client.h"
 #include "ui/aura/window.h"
@@ -610,6 +611,10 @@ void DesktopDragDropClientAuraX11::OnXdndDrop(
         event.set_flags(XGetModifiers());
       }
 
+      if (!IsDragDropInProgress()) {
+        UMA_HISTOGRAM_COUNTS("Event.DragDrop.ExternalOriginDrop", 1);
+      }
+
       drag_operation = delegate->OnPerformDrop(event);
     }
 
@@ -646,6 +651,9 @@ int DesktopDragDropClientAuraX11::StartDragAndDrop(
     const gfx::Point& root_location,
     int operation,
     ui::DragDropTypes::DragEventSource source) {
+  UMA_HISTOGRAM_ENUMERATION("Event.DragDrop.Start", source,
+                            ui::DragDropTypes::DRAG_EVENT_SOURCE_COUNT);
+
   source_current_window_ = None;
   DCHECK(!g_current_drag_drop_client);
   g_current_drag_drop_client = this;
@@ -699,6 +707,13 @@ int DesktopDragDropClientAuraX11::StartDragAndDrop(
       cursor_manager_->GetInitializedCursor(ui::kCursorGrabbing));
 
   if (alive) {
+    if (negotiated_operation_ == ui::DragDropTypes::DRAG_NONE) {
+      UMA_HISTOGRAM_ENUMERATION("Event.DragDrop.Cancel", source,
+                                ui::DragDropTypes::DRAG_EVENT_SOURCE_COUNT);
+    } else {
+      UMA_HISTOGRAM_ENUMERATION("Event.DragDrop.Drop", source,
+                                ui::DragDropTypes::DRAG_EVENT_SOURCE_COUNT);
+    }
     drag_widget_.reset();
 
     source_provider_ = NULL;
@@ -708,8 +723,11 @@ int DesktopDragDropClientAuraX11::StartDragAndDrop(
     XDeleteProperty(xdisplay_, xwindow_, atom_cache_.GetAtom(kXdndDirectSave0));
 
     return negotiated_operation_;
+  } else {

[pkotwicz, 2015/01/22 21:48:34]

Nit: No need for the "else"

if (alive) {
  ...
  return negotiated_operation_;
}
UMA_HISTOGRAM_ENUMERATION("Event.DragDrop.Cancel", source,
ui::DragDropTypes::DRAG_EVENT_SOURCE_COUNT);
return ui::DragDropTypes::DRAG_NONE;

Thanks for addressing my comments!

[caelyn, 2015/01/22 23:46:31]

Nit addressed. Thanks for giving them! :-)

+    UMA_HISTOGRAM_ENUMERATION("Event.DragDrop.Cancel", source,
+                              ui::DragDropTypes::DRAG_EVENT_SOURCE_COUNT);
+    return ui::DragDropTypes::DRAG_NONE;
   }
-  return ui::DragDropTypes::DRAG_NONE;
 }
 
 void DesktopDragDropClientAuraX11::DragUpdate(aura::Window* target,