aura: Really long tooltips should be wrapped not truncated.

ash/tooltips/tooltip_controller.h

Index: ash/tooltips/tooltip_controller.h
diff --git a/ash/tooltips/tooltip_controller.h b/ash/tooltips/tooltip_controller.h
index e2b8ed611e1d239e9fe1e3aae6d13c1ccdf6c9d7..5e9d103418ddbe905d910204ec674cb2a705a02f 100644
--- a/ash/tooltips/tooltip_controller.h
+++ b/ash/tooltips/tooltip_controller.h
@@ -60,6 +60,16 @@ class ASH_EXPORT TooltipController : public aura::client::TooltipClient,
 
   class Tooltip;
 
+  // Trims the tooltip to fit, setting |text| to the clipped result,
+  // |max_width| to the width (in pixels) of the clipped text and |line_count|
+  // to the number of lines of text in the tooltip. |x| and |y| give the
+  // location of the tooltip in screen coordinates.
+  static void TrimTooltipToFit(string16* text,
+                               int* max_width,
+                               int* line_count,
+                               int x,
+                               int y);
+
   void TooltipTimerFired();
 
   // Updates the tooltip if required (if there is any change in the tooltip