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

ui/views/widget/desktop_aura/desktop_drag_drop_client_aurax11.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/views/widget/desktop_aura/desktop_drag_drop_client_aurax11.h"
 
 #include <X11/Xatom.h>
 
 #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"
 #include "ui/aura/window_tree_host.h"
 #include "ui/base/clipboard/clipboard.h"
 #include "ui/base/dragdrop/drop_target_event.h"
 #include "ui/base/dragdrop/os_exchange_data.h"
 #include "ui/base/dragdrop/os_exchange_data_provider_aurax11.h"
 #include "ui/base/x/selection_utils.h"
 #include "ui/base/x/x11_foreign_window_manager.h"
@@ skipping 581 matching lines @@
                                 target_window_location_,
                                 target_window_root_location_,
                                 target_current_context_->GetDragOperation());
       if (target_current_context_->source_client()) {
         event.set_flags(target_current_context_->source_client()
                             ->current_modifier_state());
       } else {
         event.set_flags(XGetModifiers());
       }
 
+      if (!IsDragDropInProgress()) {
+        UMA_HISTOGRAM_COUNTS("DragDrop.ExternalOriginDrop", 1);
+      }
+
       drag_operation = delegate->OnPerformDrop(event);
     }
 
     target_window_->RemoveObserver(this);
     target_window_ = NULL;
   }
 
   XEvent xev;
   xev.xclient.type = ClientMessage;
   xev.xclient.message_type = atom_cache_.GetAtom("XdndFinished");
@@ skipping 16 matching lines @@
     XDeleteProperty(xdisplay_, xwindow_, xselection.property);
 }
 
 int DesktopDragDropClientAuraX11::StartDragAndDrop(
     const ui::OSExchangeData& data,
     aura::Window* root_window,
     aura::Window* source_window,
     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;
   waiting_on_status_ = false;
   next_position_message_.reset();
   status_received_since_enter_ = false;
   source_state_ = SOURCE_STATE_OTHER;
   drag_operation_ = operation;
   negotiated_operation_ = ui::DragDropTypes::DRAG_NONE;
 
@@ skipping 32 matching lines @@
   base::WeakPtr<DesktopDragDropClientAuraX11> alive(
       weak_ptr_factory_.GetWeakPtr());
 
   // Windows has a specific method, DoDragDrop(), which performs the entire
   // drag. We have to emulate this, so we spin off a nested runloop which will
   // track all cursor movement and reroute events to a specific handler.
   move_loop_->RunMoveLoop(
       source_window,
       cursor_manager_->GetInitializedCursor(ui::kCursorGrabbing));
 
+  if (negotiated_operation_ == ui::DragDropTypes::DRAG_NONE) {

[pkotwicz, 2015/01/22 19:00:30]

Can you please change the "alive if statement" to be the following:

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

if (negotiated_operation_ == ui::DragDropTypes::DRAG_NONE) {
  ...
} else {
  ...
}

drag_widget_.reset()

source_provider_ = NULL;
...

Can you move the UMA histograms after the "alive if". If !|alive|, accessing
|negotiated_operation_| will cause a crash. |alive| is false when the drag and
drop source browser window is closed during the drag and drop operation. An evil
browser extension can close the browser window during a drag and drop operation.
I think that this case is covered by BookmarkBarViewTest22.*

[caelyn, 2015/01/22 21:13:08]

I moved if (negotiated_operation == ...) section inside the if alive section,
and added an else to record a cancel and return DRAG_NONE

+    UMA_HISTOGRAM_ENUMERATION("DragDrop.Cancel", source,
+                              ui::DragDropTypes::DRAG_EVENT_SOURCE_COUNT);
+  } else {
+    UMA_HISTOGRAM_ENUMERATION("DragDrop.Drop", source,
+                              ui::DragDropTypes::DRAG_EVENT_SOURCE_COUNT);
+  }
+
   if (alive) {
     drag_widget_.reset();
 
     source_provider_ = NULL;
     g_current_drag_drop_client = NULL;
     drag_operation_ = 0;
     XDeleteProperty(xdisplay_, xwindow_, atom_cache_.GetAtom("XdndActionList"));
     XDeleteProperty(xdisplay_, xwindow_, atom_cache_.GetAtom(kXdndDirectSave0));
 
     return negotiated_operation_;
@@ skipping 481 matching lines @@
     for (int x = 0; x < in_bitmap->width(); ++x) {
       if (SkColorGetA(in_row[x]) > kMinAlpha)
         return true;
     }
   }
 
   return false;
 }
 
 }  // namespace views