Mac: Prevent NTP mousewheel events from being suppressed on Lion.

chrome/browser/ui/webui/ntp/ntp_resource_cache.cc

Index: chrome/browser/ui/webui/ntp/ntp_resource_cache.cc
diff --git a/chrome/browser/ui/webui/ntp/ntp_resource_cache.cc b/chrome/browser/ui/webui/ntp/ntp_resource_cache.cc
index c5dadc2e31965856a8093cb71f8c33598049762d..ccfc1161b95b60688cf5cb3b1e09e3d6bec2b3ca 100644
--- a/chrome/browser/ui/webui/ntp/ntp_resource_cache.cc
+++ b/chrome/browser/ui/webui/ntp/ntp_resource_cache.cc
@@ -58,6 +58,10 @@
 #include "chrome/browser/ui/gtk/bookmarks/bookmark_bar_gtk.h"
 #endif
 
+#if defined(OS_MACOSX)
+#include "base/mac/mac_util.h"
+#endif
+
 using base::Time;
 using content::BrowserThread;
 
@@ -176,7 +180,8 @@ bool InDateRange(double begin, double end) {
 
 }  // namespace
 
-NTPResourceCache::NTPResourceCache(Profile* profile) : profile_(profile) {
+NTPResourceCache::NTPResourceCache(Profile* profile)
+    : profile_(profile), isSwipeTrackingFromScrollEventsEnabled_(false) {
   registrar_.Add(this, chrome::NOTIFICATION_BROWSER_THEME_CHANGED,
                  content::Source<ThemeService>(
                      ThemeServiceFactory::GetForProfile(profile)));
@@ -195,13 +200,26 @@ NTPResourceCache::NTPResourceCache(Profile* profile) : profile_(profile) {
 
 NTPResourceCache::~NTPResourceCache() {}
 
+bool NTPResourceCache::InvalidateNewTabCache() {

[Evan Stade, 2012/04/17 21:29:53]

s/InvalidateNewTabCache/NewTabCacheNeedsRefresh/g

(InvalidateNewTabCache sounds like a verb rather than a question)

[Patrick Dubroy, 2012/04/18 14:43:06]

Done.

+#if defined(OS_MACOSX)
+  // Invalidate if the current value is different from the cached value.
+  bool swipe_tracking_enabled =
+      base::mac::IsSwipeTrackingFromScrollEventsEnabled();
+  if (swipe_tracking_enabled != isSwipeTrackingFromScrollEventsEnabled_) {
+    isSwipeTrackingFromScrollEventsEnabled_ = swipe_tracking_enabled;
+    return true;
+  }
+#endif
+  return false;
+}
+
 RefCountedMemory* NTPResourceCache::GetNewTabHTML(bool is_incognito) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   if (is_incognito) {
     if (!new_tab_incognito_html_.get())
       CreateNewTabIncognitoHTML();
   } else {
-    if (!new_tab_html_.get())
+    if (!new_tab_html_.get() || InvalidateNewTabCache())
       CreateNewTabHTML();
   }
   return is_incognito ? new_tab_incognito_html_.get() :
@@ -365,6 +383,17 @@ void NTPResourceCache::CreateNewTabHTML() {
   localized_strings.SetString("hideSessionMenuItemText",
       l10n_util::GetStringUTF16(IDS_POLICY_HIDE));
 
+  // On Mac OS X 10.7+, horizontal scrolling can be treated as a back or
+  // forward gesture. Pass through a flag that indicates whether or not that
+  // feature is enabled.
+#if defined(OS_MACOSX)
+  localized_strings.SetBoolean("isSwipeTrackingFromScrollEventsEnabled",
+      base::mac::IsSwipeTrackingFromScrollEventsEnabled());

[Evan Stade, 2012/04/17 21:29:53]

use the member var to avoid these ifdefs

[Patrick Dubroy, 2012/04/18 14:43:06]

Done.

+#else
+  localized_strings.SetBoolean("isSwipeTrackingFromScrollEventsEnabled",
+      false);
+#endif
+
 #if defined(OS_CHROMEOS)
   localized_strings.SetString("expandMenu",
       l10n_util::GetStringUTF16(IDS_NEW_TAB_CLOSE_MENU_EXPAND));