[TooManyTabs] Add TabNavigationThrottle

chrome/browser/resource_coordinator/background_tab_navigation_throttle.cc

Index: chrome/browser/resource_coordinator/background_tab_navigation_throttle.cc
diff --git a/chrome/browser/resource_coordinator/background_tab_navigation_throttle.cc b/chrome/browser/resource_coordinator/background_tab_navigation_throttle.cc
new file mode 100644
index 0000000000000000000000000000000000000000..0dd405d89181f453957a0f5014aa2f260ac98e59
--- /dev/null
+++ b/chrome/browser/resource_coordinator/background_tab_navigation_throttle.cc
@@ -0,0 +1,72 @@
+// Copyright 2017 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/resource_coordinator/background_tab_navigation_throttle.h"
+
+#include "base/feature_list.h"
+#include "base/memory/ptr_util.h"
+#include "chrome/browser/browser_process.h"
+#include "chrome/browser/profiles/profile.h"
+#include "chrome/browser/resource_coordinator/tab_manager.h"
+#include "chrome/browser/search/search.h"
+#include "chrome/common/chrome_features.h"
+#include "content/public/browser/navigation_handle.h"
+#include "content/public/browser/web_contents.h"
+
+namespace resource_coordinator {
+
+// static
+std::unique_ptr<BackgroundTabNavigationThrottle>
+BackgroundTabNavigationThrottle::MaybeCreateThrottleFor(
+    content::NavigationHandle* navigation_handle) {
+  if (!base::FeatureList::IsEnabled(features::kStaggeredBackgroundTabOpen))
+    return nullptr;
+
+  // Only consider main frames because this is to delay tabs.
+  if (!navigation_handle->IsInMainFrame())
+    return nullptr;
+
+  // Never delay foreground tabs.
+  if (navigation_handle->GetWebContents()->IsVisible())
+    return nullptr;
+
+  // Never delay the tab when there is opener, so the created window can talk
+  // to the creator immediately.
+  if (navigation_handle->GetWebContents()->HasOpener())
+    return nullptr;
+
+  // Only delay the first navigation in a newly created tab.
+  if (!navigation_handle->GetWebContents()
+           ->GetController()
+           .IsInitialNavigation()) {
+    return nullptr;
+  }
+
+  // Only consider delaying common URLs, i.e., HTTP/HTTPS and common
+  // chrome:// UI URLs.
+  if (!navigation_handle->GetURL().SchemeIsHTTPOrHTTPS() &&
+      !TabManager::IsInternalPage(navigation_handle->GetURL())) {

[Charlie Reis, 2017/07/06 23:50:30]

As noted earlier, I don't understand why we need this URL check.  Maybe there's
a better way to handle it?

[Zhen Wang, 2017/07/07 18:06:39]

Maybe we do not need any URL check here. I was just trying to be conservative. I
removed the check now. We can add back some specific check here later if needed.

[Charlie Reis, 2017/07/07 22:07:56]

Acknowledged.

+    return nullptr;
+  }
+
+  return base::MakeUnique<BackgroundTabNavigationThrottle>(navigation_handle);
+}
+
+const char* BackgroundTabNavigationThrottle::GetNameForLogging() {
+  return "BackgroundTabNavigationThrottle";
+}
+
+BackgroundTabNavigationThrottle::BackgroundTabNavigationThrottle(
+    content::NavigationHandle* navigation_handle)
+    : content::NavigationThrottle(navigation_handle) {}
+
+BackgroundTabNavigationThrottle::~BackgroundTabNavigationThrottle() {}
+
+content::NavigationThrottle::ThrottleCheckResult
+BackgroundTabNavigationThrottle::WillStartRequest() {
+  return g_browser_process->GetTabManager()->MaybeThrottleNavigation(
+      navigation_handle());
+}
+
+}  // namespace resource_coordinator