[MacViews] Enable dragging a window by its caption/draggable areas.

chrome/browser/ui/views/frame/browser_non_client_frame_view_mac.mm

 // Copyright 2015 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 "chrome/browser/ui/views/frame/browser_non_client_frame_view_mac.h"
 
 #include "chrome/browser/themes/theme_properties.h"
 #include "chrome/browser/ui/views/frame/browser_frame.h"
 #include "chrome/browser/ui/views/frame/browser_view.h"
 #include "chrome/browser/ui/views/frame/browser_view_layout.h"
@@ skipping 51 matching lines @@
 gfx::Rect BrowserNonClientFrameViewMac::GetBoundsForClientView() const {
   return bounds();
 }
 
 gfx::Rect BrowserNonClientFrameViewMac::GetWindowBoundsForClientBounds(
     const gfx::Rect& client_bounds) const {
   return client_bounds;
 }
 
 int BrowserNonClientFrameViewMac::NonClientHitTest(const gfx::Point& point) {
-  return frame()->client_view()->NonClientHitTest(point);
+  int component = frame()->client_view()->NonClientHitTest(point);
+
+  // BrowserView::NonClientHitTest will return HTNOWHERE for points that hit
+  // the native title bar. On Mac, we need to explicitly return HTCAPTION for
+  // those points.
+  if (component == HTNOWHERE && bounds().Contains(point))
+    return HTCAPTION;
+
+  return component;
 }
 
 void BrowserNonClientFrameViewMac::GetWindowMask(const gfx::Size& size,
                                                  gfx::Path* window_mask) {
 }
 
 void BrowserNonClientFrameViewMac::ResetWindowControls() {
 }
 
 void BrowserNonClientFrameViewMac::UpdateWindowIcon() {
@@ skipping 75 matching lines @@
 
   // Draw the tabstrip/toolbar separator.
   canvas->TileImageInt(*border, 0, 0, x, y, w, border->height());
 
   // Draw the content/toolbar separator.
   canvas->FillRect(
       gfx::Rect(x, y + h - kClientEdgeThickness, w, kClientEdgeThickness),
       ThemeProperties::GetDefaultColor(
           ThemeProperties::COLOR_TOOLBAR_SEPARATOR));
 }