MacViews: Handle three-finger swipe gestures for navigation.

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

 // Copyright 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.
 
 #include "chrome/browser/ui/views/frame/browser_view.h"
 
 #include <stdint.h>
 
 #include <algorithm>
 #include <memory>
@@ skipping 253 matching lines @@
   PaintBackgroundAttachedMode(canvas, view->GetThemeProvider(),
                               view->GetLocalBounds(), background_image_offset);
   if (view->height() >= toolbar_overlap) {
     BrowserView::Paint1pxHorizontalLine(
         canvas, view->GetThemeProvider()->GetColor(
                     ThemeProperties::COLOR_TOOLBAR_BOTTOM_SEPARATOR),
         view->GetLocalBounds(), true);
   }
 }
 
+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
 
 ///////////////////////////////////////////////////////////////////////////////
 // Delegate implementation for BrowserViewLayout. Usually just forwards calls
 // into BrowserView.
 class BrowserViewLayoutDelegateImpl : public BrowserViewLayoutDelegate {
  public:
   explicit BrowserViewLayoutDelegateImpl(BrowserView* browser_view)
       : browser_view_(browser_view) {}
   ~BrowserViewLayoutDelegateImpl() override {}
@@ skipping 1647 matching lines @@
   if (!initialized_ || in_process_fullscreen_)
     return;
 
   views::View::Layout();
 
   // TODO(jamescook): Why was this in the middle of layout code?
   toolbar_->location_bar()->omnibox_view()->SetFocusBehavior(
       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()) {
     InitViews();
     initialized_ = true;
   }
 }
 
 void BrowserView::ChildPreferredSizeChanged(View* child) {
   Layout();
@@ skipping 686 matching lines @@
 }
 
 extensions::ActiveTabPermissionGranter*
 BrowserView::GetActiveTabPermissionGranter() {
   content::WebContents* web_contents = GetActiveWebContents();
   if (!web_contents)
     return nullptr;
   return extensions::TabHelper::FromWebContents(web_contents)
       ->active_tab_permission_granter();
 }