Don't spin the loading indicator for in-page navigations.

chrome/browser/ui/cocoa/tabs/tab_strip_controller.mm

 // 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.
 
 #import "chrome/browser/ui/cocoa/tabs/tab_strip_controller.h"
 
 #import <QuartzCore/QuartzCore.h>
 
 #include <cmath>
 #include <limits>
@@ skipping 1561 matching lines @@
 
   TabLoadingState oldState = [tabController loadingState];
   TabLoadingState newState = kTabDone;
   NSImage* throbberImage = nil;
   if (contents->IsCrashed()) {
     newState = kTabCrashed;
     newHasIcon = true;
   } else if (contents->IsWaitingForResponse()) {
     newState = kTabWaiting;
     throbberImage = throbberWaitingImage;
-  } else if (contents->IsLoading()) {
+  } else if (contents->IsLoadingToDifferentDocument()) {
     newState = kTabLoading;
     throbberImage = throbberLoadingImage;
   }
 
   if (oldState != newState)
     [tabController setLoadingState:newState];
 
   // While loading, this function is called repeatedly with the same state.
   // To avoid expensive unnecessary view manipulation, only make changes when
   // the state is actually changing.  When loading is complete (kTabDone),
@@ skipping 636 matching lines @@
 NSView* GetSheetParentViewForWebContents(WebContents* web_contents) {
   // View hierarchy of the contents view:
   // NSView  -- switchView, same for all tabs
   // +- NSView  -- TabContentsController's view
   //    +- TabContentsViewCocoa
   //
   // Changing it? Do not forget to modify
   // -[TabStripController swapInTabAtIndex:] too.
   return [web_contents->GetNativeView() superview];
 }