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

ash/drag_drop/drag_drop_controller.cc

Index: ash/drag_drop/drag_drop_controller.cc
diff --git a/ash/drag_drop/drag_drop_controller.cc b/ash/drag_drop/drag_drop_controller.cc
index 695c7737865c0919e3f86337ba8d7f80e870aa1b..7b8f2cd36dea2201b033334b661828fece8ef0d4 100644
--- a/ash/drag_drop/drag_drop_controller.cc
+++ b/ash/drag_drop/drag_drop_controller.cc
@@ -9,6 +9,7 @@
 #include "ash/shell.h"
 #include "base/bind.h"
 #include "base/message_loop/message_loop.h"
+#include "base/metrics/histogram_macros.h"
 #include "base/run_loop.h"
 #include "ui/aura/client/capture_client.h"
 #include "ui/aura/env.h"
@@ -159,6 +160,9 @@ int DragDropController::StartDragAndDrop(
       provider->GetDragImage().size().IsEmpty())
     return 0;
 
+  UMA_HISTOGRAM_ENUMERATION("DragDrop.Start", source,
+                            ui::DragDropTypes::DRAG_EVENT_SOURCE_COUNT);
+
   current_drag_event_source_ = source;
   DragDropTracker* tracker =
       new DragDropTracker(root_window, drag_drop_window_delegate_.get());
@@ -310,10 +314,15 @@ void DragDropController::Drop(aura::Window* target,
         *drag_data_, event.location(), event.root_location(), drag_operation_);
     e.set_flags(event.flags());
     drag_operation_ = delegate->OnPerformDrop(e);
-    if (drag_operation_ == 0)
+    if (drag_operation_ == 0) {
+      UMA_HISTOGRAM_ENUMERATION("DragDrop.Cancel", current_drag_event_source_,
+                                ui::DragDropTypes::DRAG_EVENT_SOURCE_COUNT);
       StartCanceledAnimation(kCancelAnimationDuration);
-    else
+    } else {
+      UMA_HISTOGRAM_ENUMERATION("DragDrop.Drop", current_drag_event_source_,
+                                ui::DragDropTypes::DRAG_EVENT_SOURCE_COUNT);
       drag_image_.reset();
+    }
   } else {
     drag_image_.reset();
   }
@@ -324,6 +333,8 @@ void DragDropController::Drop(aura::Window* target,
 }
 
 void DragDropController::DragCancel() {
+  UMA_HISTOGRAM_ENUMERATION("DragDrop.Cancel", current_drag_event_source_,
+                            ui::DragDropTypes::DRAG_EVENT_SOURCE_COUNT);
   DoDragCancel(kCancelAnimationDuration);
 }
 
@@ -482,9 +493,9 @@ void DragDropController::AnimationEnded(const gfx::Animation* animation) {
     drag_image_.reset();
   if (pending_long_tap_) {
     // If not in a nested message loop, we can forward the long tap right now.
-    if (!should_block_during_drag_drop_)
+    if (!should_block_during_drag_drop_) {
       ForwardPendingLongTap();
-    else {
+    } else {
       // See comment about this in OnGestureEvent().
       base::MessageLoopForUI::current()->PostTask(
           FROM_HERE,