ash:Shelf - Added UMA stats for ShelfAlignment

ash/launcher/launcher_view.cc

Index: ash/launcher/launcher_view.cc
diff --git a/ash/launcher/launcher_view.cc b/ash/launcher/launcher_view.cc
index 4279c3c569019121323b1b401f8129709bfae1bd..8d8fc1f054dcd7091973f4ed4c479f26be07e802 100644
--- a/ash/launcher/launcher_view.cc
+++ b/ash/launcher/launcher_view.cc
@@ -27,6 +27,7 @@
 #include "ash/shell_delegate.h"
 #include "base/auto_reset.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/metrics/histogram.h"
 #include "grit/ash_resources.h"
 #include "grit/ash_strings.h"
 #include "ui/aura/client/screen_position_client.h"
@@ -58,6 +59,11 @@ using views::View;
 namespace ash {
 namespace internal {
 
+const int SHELF_ALIGNMENT_UMA_ENUM_VALUE_BOTTOM = 0;
+const int SHELF_ALIGNMENT_UMA_ENUM_VALUE_LEFT = 1;
+const int SHELF_ALIGNMENT_UMA_ENUM_VALUE_RIGHT = 2;
+const int SHELF_ALIGNMENT_UMA_ENUM_VALUE_COUNT = 3;
+
 // Default amount content is inset on the left edge.
 const int kDefaultLeadingInset = 8;
 
@@ -1554,6 +1560,13 @@ void LauncherView::PointerPressedOnButton(views::View* view,
 
   ShelfLayoutManager* shelf = tooltip_->shelf_layout_manager();
 
+  UMA_HISTOGRAM_ENUMERATION("Ash.ShelfAlignmentUsage",

[James Cook, 2013/10/16 23:35:27]

This feels like the wrong way to do this. It will skew the results toward people
who use the shelf heavily. We need some equivalent of "usage minutes" or "page
loads".

One way might be to look in metrics_service.cc at how it collects memory
information periodically.  Another might be to add an ash "periodic stats"
function that gets called periodically on a timer via PostDelayedTask.

+      shelf->SelectValueForShelfAlignment(SHELF_ALIGNMENT_UMA_ENUM_VALUE_BOTTOM,
+                                          SHELF_ALIGNMENT_UMA_ENUM_VALUE_LEFT,
+                                          SHELF_ALIGNMENT_UMA_ENUM_VALUE_RIGHT,
+                                          -1),
+      SHELF_ALIGNMENT_UMA_ENUM_VALUE_COUNT);
+
   drag_view_ = view;
   drag_offset_ = shelf->PrimaryAxisValue(event.x(), event.y());
 }