mac: Always do history swiping on the NTP on lion devices with touchpad.

chrome/browser/renderer_host/chrome_render_widget_host_view_mac_delegate.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/renderer_host/chrome_render_widget_host_view_mac_delegate.h"
 
 #include <cmath>
 
 #include "base/sys_string_conversions.h"
 #include "chrome/browser/debugger/devtools_window.h"
 #include "chrome/browser/spellchecker/spellcheck_platform_mac.h"
 #include "chrome/browser/ui/browser.h"
 #include "chrome/browser/ui/browser_list.h"
 #import "chrome/browser/ui/cocoa/history_overlay_controller.h"
 #import "chrome/browser/ui/cocoa/view_id_util.h"
 #include "chrome/common/spellcheck_messages.h"
+#include "chrome/common/url_constants.h"
 #include "content/browser/mac/closure_blocks_leopard_compat.h"
 #include "content/browser/renderer_host/render_view_host.h"
 #include "content/browser/renderer_host/render_widget_host.h"
 #include "content/browser/renderer_host/render_widget_host_view.h"
 #include "content/public/browser/render_view_host_observer.h"
+#include "content/public/browser/web_contents.h"
 
 // Declare things that are part of the 10.7 SDK.
 #if !defined(MAC_OS_X_VERSION_10_7) || \
     MAC_OS_X_VERSION_MAX_ALLOWED < MAC_OS_X_VERSION_10_7
 enum {
   NSEventPhaseNone        = 0, // event not associated with a phase.
   NSEventPhaseBegan       = 0x1 << 0,
   NSEventPhaseStationary  = 0x1 << 1,
   NSEventPhaseChanged     = 0x1 << 2,
   NSEventPhaseEnded       = 0x1 << 3,
@@ skipping 97 matching lines @@
 }
 
 - (BOOL)handleEvent:(NSEvent*)event {
   if ([event type] == NSScrollWheel)
     return [self maybeHandleHistorySwiping:event];
 
   return NO;
 }
 
 - (void)gotUnhandledWheelEvent {
-  gotUnhandledWheelEvent_ = true;
+  gotUnhandledWheelEvent_ = YES;
 }
 
 - (void)scrollOffsetPinnedToLeft:(BOOL)left toRight:(BOOL)right {
   isPinnedLeft_ = left;
   isPinnedRight_ = right;
 }
 
 - (void)setHasHorizontalScrollbar:(BOOL)has_horizontal_scrollbar {
   hasHorizontalScrollbar_ = has_horizontal_scrollbar;
 }
 
 // Checks if |theEvent| should trigger history swiping, and if so, does
 // history swiping. Returns YES if the event was consumed or NO if it should
 // be passed on to the renderer.
 - (BOOL)maybeHandleHistorySwiping:(NSEvent*)theEvent {
   BOOL canUseLionApis = [theEvent respondsToSelector:@selector(phase)];
   if (!canUseLionApis)
     return NO;
 
   // Scroll events always go to the web first, and can only trigger history
   // swiping if they come back unhandled.
   if ([theEvent phase] == NSEventPhaseBegan) {
     totalScrollDelta_ = NSZeroSize;
-    gotUnhandledWheelEvent_ = false;
+    gotUnhandledWheelEvent_ = NO;
   }
 
   if (!render_widget_host_ || !render_widget_host_->IsRenderView())
     return NO;
   bool isDevtoolsRwhv = DevToolsWindow::IsDevToolsWindow(
       static_cast<RenderViewHost*>(render_widget_host_));
   if (isDevtoolsRwhv)
     return NO;
 
+  // TODO(thakis): This is wrong, as it will navigate the frontmost browser
+  // for swipe events on background windows. It also navigates the frontmost
+  // browser for swipes on extensions popups. And it's a dependency problem,
+  // too. http://crbug.com/102541
+  Browser* browser = BrowserList::GetLastActive();
+
+  if (browser && [NSEvent isSwipeTrackingFromScrollEventsEnabled]) {
+    content::WebContents* contents = browser->GetSelectedWebContents();
+    if (contents && contents->GetURL() == GURL(chrome::kChromeUINewTabURL)) {
+      // Always do history navigation on the NTP if it's enabled.
+      gotUnhandledWheelEvent_ = YES;
+    }
+  }
+
   if (gotUnhandledWheelEvent_ &&
       [NSEvent isSwipeTrackingFromScrollEventsEnabled] &&
       [theEvent phase] == NSEventPhaseChanged) {
     totalScrollDelta_.width += [theEvent scrollingDeltaX];
     totalScrollDelta_.height += [theEvent scrollingDeltaY];
 
     bool isHorizontalGesture =
       std::abs(totalScrollDelta_.width) > std::abs(totalScrollDelta_.height);
 
     bool isRightScroll = [theEvent scrollingDeltaX] < 0;
     bool goForward = isRightScroll;
     bool canGoBack = false, canGoForward = false;
-    if (Browser* browser = BrowserList::GetLastActive()) {
+    if (browser) {
       canGoBack = browser->CanGoBack();
       canGoForward = browser->CanGoForward();
     }
 
     // If "forward" is inactive and the user rubber-bands to the right,
     // "isPinnedLeft" will be false.  When the user then rubber-bands to the
     // left in the same gesture, that should trigger history immediately if
     // there's no scrollbar, hence the check for hasHorizontalScrollbar_.
     bool shouldGoBack = isPinnedLeft_ || !hasHorizontalScrollbar_;
     bool shouldGoForward = isPinnedRight_ || !hasHorizontalScrollbar_;
@@ skipping 60 matching lines @@
 
           [historyOverlay setProgress:gestureAmount];
           if (isComplete) {
             [historyOverlay dismiss];
             [historyOverlay release];
           }
         }];
       return YES;
     }
   }
-  return NO;
+  return gotUnhandledWheelEvent_;
 }
 
 - (BOOL)validateUserInterfaceItem:(id<NSValidatedUserInterfaceItem>)item
                       isValidItem:(BOOL*)valid {
   SEL action = [item action];
 
   // For now, this action is always enabled for render view;
   // this is sub-optimal.
   // TODO(suzhe): Plumb the "can*" methods up from WebCore.
   if (action == @selector(checkSpelling:)) {
@@ skipping 64 matching lines @@
 }
 
 - (void)spellCheckEnabled:(BOOL)enabled checked:(BOOL)checked {
   spellcheck_enabled_ = enabled;
   spellcheck_checked_ = checked;
 }
 
 // END Spellchecking methods
 
 @end