Change how the insertion point for tab drags is calculated.

chrome/browser/ui/views/tabs/tab.h

 // 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.
 
 #ifndef CHROME_BROWSER_UI_VIEWS_TABS_TAB_H_
 #define CHROME_BROWSER_UI_VIEWS_TABS_TAB_H_
 
 #include <list>
 #include <string>
 
@@ skipping 81 matching lines @@
   // this tab. Only used for collecting UMA metrics.
   // See ash/touch/touch_uma.cc.
   bool tab_activated_with_last_gesture_begin() const {
     return tab_activated_with_last_gesture_begin_;
   }
 
   views::GlowHoverController* hover_controller() {
     return &hover_controller_;
   }
 
+  // Returns the inset within the first dragged tab to use when calculating the
+  // "drag insertion point".  If we simply used the x-coordinate of the tab,
+  // we'd be calculating based on a point well before where the user considers
+  // the tab to "be".  The value here is chosen to "feel good" based on the
+  // widths of the tab images and the tab overlap.
+  //
+  // Note that this must return a value smaller than the midpoint of any tab's
+  // width, or else the user won't be able to drag a tab to the left of the
+  // first tab in the strip.
+  static int leading_width_for_drag() { return 16; }
+
   // Returns the minimum possible size of a single unselected Tab.
   static gfx::Size GetMinimumUnselectedSize();
   // Returns the minimum possible size of a selected Tab. Selected tabs must
   // always show a close button and have a larger minimum size than unselected
   // tabs.
   static gfx::Size GetMinimumSelectedSize();
   // Returns the preferred size of a single Tab, assuming space is
   // available.
   static gfx::Size GetStandardSize();
 
@@ skipping 249 matching lines @@
   SkColor close_button_color_;
 
   // As the majority of the tabs are inactive, and painting tabs is slowish,
   // we cache a handful of the inactive tab backgrounds here.
   static ImageCache* image_cache_;
 
   DISALLOW_COPY_AND_ASSIGN(Tab);
 };
 
 #endif  // CHROME_BROWSER_UI_VIEWS_TABS_TAB_H_