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 1c7b819177667b8aec8476aee8334c61cd65f5dd..154247edc2600a1fe067fba95f1fcdb47731950e 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.h"
 #include "base/run_loop.h"
 #include "ui/aura/client/capture_client.h"
 #include "ui/aura/env.h"
@@ -159,6 +160,12 @@ int DragDropController::StartDragAndDrop(
       provider->GetDragImage().size().IsEmpty())
     return 0;
 
+  if (source == ui::DragDropTypes::DRAG_EVENT_SOURCE_TOUCH) {
+    UMA_HISTOGRAM_COUNTS("DragDrop.Touch.Start", 1);

[mfomitchev, 2015/01/08 23:30:59]

I think a single shared UMA_HISTOGRAM_ENUMERATION histogram would make more
sense here.

[caelyn, 2015/01/12 22:43:10]

I made the changes in histograms.xml and elsewhere - was that what you had in
mind?

+  } else if (source == ui::DragDropTypes::DRAG_EVENT_SOURCE_MOUSE) {
+    UMA_HISTOGRAM_COUNTS("DragDrop.Mouse.Start", 1);
+  }
+
   current_drag_event_source_ = source;
   DragDropTracker* tracker =
       new DragDropTracker(root_window, drag_drop_window_delegate_.get());
@@ -310,10 +317,18 @@ 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) {
       StartCanceledAnimation(kCancelAnimationDuration);

[mfomitchev, 2015/01/08 23:30:59]

don't we need to log a Cancel here?

[caelyn, 2015/01/12 22:43:10]

Done. This changes the semantics of cancel to be logged whenever a DnD event
doesn't end in a drop event.

-    else
+    } else {
+      if (current_drag_event_source_ ==
+          ui::DragDropTypes::DRAG_EVENT_SOURCE_TOUCH) {
+        UMA_HISTOGRAM_COUNTS("DragDrop.Touch.Drop", 1);
+      } else if (current_drag_event_source_ ==
+                 ui::DragDropTypes::DRAG_EVENT_SOURCE_MOUSE) {
+        UMA_HISTOGRAM_COUNTS("DragDrop.Mouse.Drop", 1);
+      }
       drag_image_.reset();
+    }
   } else {
     drag_image_.reset();
   }
@@ -324,6 +339,13 @@ void DragDropController::Drop(aura::Window* target,
 }
 
 void DragDropController::DragCancel() {
+  if (current_drag_event_source_ ==
+      ui::DragDropTypes::DRAG_EVENT_SOURCE_TOUCH) {
+    UMA_HISTOGRAM_COUNTS("DragDrop.Touch.Cancel", 1);
+  } else if (current_drag_event_source_ ==
+             ui::DragDropTypes::DRAG_EVENT_SOURCE_MOUSE) {
+    UMA_HISTOGRAM_COUNTS("DragDrop.Mouse.Cancel", 1);
+  }
   DoDragCancel(kCancelAnimationDuration);
 }