MacViews: Handle three-finger swipe gestures for navigation.

chrome/browser/ui/views/frame/browser_view.cc

Index: chrome/browser/ui/views/frame/browser_view.cc
diff --git a/chrome/browser/ui/views/frame/browser_view.cc b/chrome/browser/ui/views/frame/browser_view.cc
index f4dbf87a9b3440d7ce19808cf32bf6b2c92f3fe7..81c6b98da8e53b9ef97b548a10bb8d694ddb6035 100644
--- a/chrome/browser/ui/views/frame/browser_view.cc
+++ b/chrome/browser/ui/views/frame/browser_view.cc
@@ -271,6 +271,20 @@ void PaintAttachedBookmarkBar(gfx::Canvas* canvas,
   }
 }
 
+bool GetGestureCommand(ui::GestureEvent* event, int* command) {
+  DCHECK(command);
+  *command = 0;
+#if defined(OS_MACOSX)
+  if (event->details().type() == ui::ET_GESTURE_SWIPE) {
+    if (event->details().swipe_left())
+      *command = IDC_BACK;

[sky, 2017/02/22 17:34:10]

I would early return here and on 282, then 285 becomes return false.

[themblsha, 2017/02/27 11:49:16]

Ok, I thought my code would make it easier to be right as there's less chance of
doing an early 'return false' with a correctly initialized command, but maybe
it's too clever.

+    else if (event->details().swipe_right())
+      *command = IDC_FORWARD;
+  }
+#endif  // OS_MACOSX
+  return *command != 0;
+}
+
 }  // namespace
 
 ///////////////////////////////////////////////////////////////////////////////
@@ -1938,6 +1952,18 @@ void BrowserView::Layout() {
       IsToolbarVisible() ? FocusBehavior::ALWAYS : FocusBehavior::NEVER);
 }
 
+void BrowserView::OnGestureEvent(ui::GestureEvent* event) {
+  int command;
+  if (GetGestureCommand(event, &command) &&
+      chrome::IsCommandEnabled(browser(), command)) {
+    chrome::ExecuteCommandWithDisposition(
+        browser(), command, ui::DispositionFromEventFlags(event->flags()));
+    return;
+  }
+
+  ClientView::OnGestureEvent(event);
+}
+
 void BrowserView::ViewHierarchyChanged(
     const ViewHierarchyChangedDetails& details) {
   if (!initialized_ && details.is_add && details.child == this && GetWidget()) {