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..61ecdecced1c385bce4df4b8e0ebeaaa331cfe5a 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"
@@ -417,6 +418,7 @@ DesktopDragDropClientAuraX11::DesktopDragDropClientAuraX11(
       source_current_window_(None),
       source_state_(SOURCE_STATE_OTHER),
       drag_operation_(0),
+      current_drag_event_source_(ui::DragDropTypes::DRAG_EVENT_SOURCE_MOUSE),
       negotiated_operation_(ui::DragDropTypes::DRAG_NONE),
       weak_ptr_factory_(this) {
   // Some tests change the DesktopDragDropClientAuraX11 associated with an
@@ -646,6 +648,9 @@ int DesktopDragDropClientAuraX11::StartDragAndDrop(
     const gfx::Point& root_location,
     int operation,
     ui::DragDropTypes::DragEventSource source) {
+  UMA_HISTOGRAM_ENUMERATION("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;
@@ -655,6 +660,7 @@ int DesktopDragDropClientAuraX11::StartDragAndDrop(
   source_state_ = SOURCE_STATE_OTHER;
   drag_operation_ = operation;
   negotiated_operation_ = ui::DragDropTypes::DRAG_NONE;
+  current_drag_event_source_ = source;

[pkotwicz, 2015/01/14 18:31:30]

Chrome for Desktop Linux does not support initiating drag and drop via touch at
all. We would need to change X11WholeScreenMoveLoop::DispatchEvent() and find
out whether we need to block events while a touch drag is in progress.

[caelyn, 2015/01/14 20:00:26]

I know that chrome on linux does not support touch events; but I thought I'd add
support for them anyway since the added complexity is very small and it saves
having ui::DragDropTypes::DRAG_EVENT_SOURCE_MOUSE duplicated three times
(currently DragDrop.Start uses source; but if I switched to using a constant for
the other two, I would switch it as well).  

I don't have strong feelings on it, since, right now, adding back support for
touch events if they do start being supported is really small. If you feel the
added complexity isn't worth it, I'll take it out.

[pkotwicz, 2015/01/14 20:39:55]

Once you move all of the histograms to this method you would be able to remove
|current_drag_event_source_| so I am ok with passing |source| to
UMA_HISTOGRAM_ENUMERATION().

[caelyn, 2015/01/21 16:29:53]

Done.

 
   const ui::OSExchangeData::Provider* provider = &data.provider();
   source_provider_ = static_cast<const ui::OSExchangeDataProviderAuraX11*>(
@@ -723,6 +729,8 @@ void DesktopDragDropClientAuraX11::Drop(aura::Window* target,
 }
 
 void DesktopDragDropClientAuraX11::DragCancel() {
+  // EndMoveLoop will call DesktopDragDropClientAuraX11::OnMoveLoopEnded and

[mfomitchev, 2015/01/14 17:03:41]

IMHO this is not really worth explaining in a comment here.

[caelyn, 2015/01/21 16:29:53]

Done.

+  // record a DragDrop.Cancel event in UMA
   move_loop_->EndMoveLoop();
 }
 
@@ -800,6 +808,13 @@ void DesktopDragDropClientAuraX11::OnMouseReleased() {
 }
 
 void DesktopDragDropClientAuraX11::OnMoveLoopEnded() {
+  if (negotiated_operation_ == ui::DragDropTypes::DRAG_NONE) {
+    UMA_HISTOGRAM_ENUMERATION("DragDrop.Cancel", current_drag_event_source_,
+                              ui::DragDropTypes::DRAG_EVENT_SOURCE_COUNT);
+  } else {
+    UMA_HISTOGRAM_ENUMERATION("DragDrop.Drop", current_drag_event_source_,
+                              ui::DragDropTypes::DRAG_EVENT_SOURCE_COUNT);
+  }
   if (source_current_window_ != None) {
     SendXdndLeave(source_current_window_);
     source_current_window_ = None;