[TooManyTabs] Add TabNavigationThrottle

chrome/browser/resource_coordinator/tab_manager.cc

 // 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.
 
 #include "chrome/browser/resource_coordinator/tab_manager.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <set>
 #include <vector>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
-#include "base/command_line.h"
 #include "base/feature_list.h"
 #include "base/macros.h"
 #include "base/memory/memory_pressure_monitor.h"
 #include "base/metrics/field_trial.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/observer_list.h"
 #include "base/process/process.h"
 #include "base/rand_util.h"
 #include "base/strings/string16.h"
 #include "base/strings/string_number_conversions.h"
@@ skipping 10 matching lines @@
 #include "chrome/browser/resource_coordinator/tab_manager_observer.h"
 #include "chrome/browser/resource_coordinator/tab_manager_web_contents_data.h"
 #include "chrome/browser/ui/browser.h"
 #include "chrome/browser/ui/browser_list.h"
 #include "chrome/browser/ui/browser_window.h"
 #include "chrome/browser/ui/tab_contents/tab_contents_iterator.h"
 #include "chrome/browser/ui/tabs/tab_strip_model.h"
 #include "chrome/browser/ui/tabs/tab_utils.h"
 #include "chrome/common/chrome_constants.h"
 #include "chrome/common/chrome_features.h"
-#include "chrome/common/chrome_switches.h"
 #include "chrome/common/url_constants.h"
 #include "components/metrics/system_memory_stats_recorder.h"
 #include "components/variations/variations_associated_data.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/navigation_controller.h"
+#include "content/public/browser/navigation_handle.h"
 #include "content/public/browser/render_process_host.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/common/page_importance_signals.h"
 
 #if defined(OS_CHROMEOS)
 #include "ash/multi_profile_uma.h"
 #include "ash/shell_port.h"
 #include "chrome/browser/resource_coordinator/tab_manager_delegate_chromeos.h"
 #include "components/user_manager/user_manager.h"
 #endif
@@ skipping 42 matching lines @@
 
 TabManager::TabManager()
     : discard_count_(0),
       recent_tab_discard_(false),
       discard_once_(false),
 #if !defined(OS_CHROMEOS)
       minimum_protection_time_(base::TimeDelta::FromMinutes(10)),
 #endif
       browser_tab_strip_tracker_(this, nullptr, nullptr),
       test_tick_clock_(nullptr),
+      loading_contents_(nullptr),
       weak_ptr_factory_(this) {
 #if defined(OS_CHROMEOS)
   delegate_.reset(new TabManagerDelegate(weak_ptr_factory_.GetWeakPtr()));
 #endif
   browser_tab_strip_tracker_.Init();
 }
 
 TabManager::~TabManager() {
   Stop();
 }
@@ skipping 655 matching lines @@
   // When ActiveTabChanged, |new_contents| purged state changes to be false.
   GetWebContentsData(new_contents)->set_is_purged(false);
   // If |old_contents| is set, that tab has switched from being active to
   // inactive, so record the time of that transition.
   if (old_contents) {
     GetWebContentsData(old_contents)->SetLastInactiveTime(NowTicks());
     // Re-setting time-to-purge every time a tab becomes inactive.
     GetWebContentsData(old_contents)
         ->set_time_to_purge(GetTimeToPurge(min_time_to_purge_));
   }
+
+  ResumeTabNavigationIfNeeded(new_contents);
 }
 
 void TabManager::TabInsertedAt(TabStripModel* tab_strip_model,
                                content::WebContents* contents,
                                int index,
                                bool foreground) {
   // Only interested in background tabs, as foreground tabs get taken care of by
   // ActiveTabChanged.
   if (foreground)
     return;
@@ skipping 69 matching lines @@
   // TODO(georgesak): Add Linux when automatic discarding is enabled for that
   // platform.
   std::string allow_multiple_discards = variations::GetVariationParamValue(
       features::kAutomaticTabDiscarding.name, "AllowMultipleDiscards");
   return (allow_multiple_discards != "true");
 #else
   return false;
 #endif
 }
 
+content::NavigationThrottle::ThrottleCheckResult
+TabManager::MaybeThrottleNavigation(
+    content::NavigationHandle* navigation_handle) {
+  if (!ShouldDelayNavigation(navigation_handle)) {
+    loading_contents_ = navigation_handle->GetWebContents();
+    return content::NavigationThrottle::PROCEED;
+  }
+
+  pending_navigations_.push_back(navigation_handle);
+  return content::NavigationThrottle::DEFER;
+}
+
+bool TabManager::ShouldDelayNavigation(
+    content::NavigationHandle* navigation_handle) const {
+  if (!navigation_handle)
+    return false;
+
+  // Do not throttle the navigation if no tab is currently loading.
+  if (!loading_contents_) {
+    return false;
+  }
+
+  return true;
+}
+
+void TabManager::HasFinishedLoadingTab(content::WebContents* contents) {
+  loading_contents_ = nullptr;
+
+  while (!pending_navigations_.empty()) {
+    content::NavigationHandle* navigation_handle = pending_navigations_.front();
+    pending_navigations_.erase(pending_navigations_.begin());
+
+    if (navigation_handle) {
+      loading_contents_ = navigation_handle->GetWebContents();
+      navigation_handle->Resume();
+      break;
+    }
+  }
+}
+
+void TabManager::ResumeTabNavigationIfNeeded(content::WebContents* contents) {
+  auto it = pending_navigations_.begin();
+  while (it != pending_navigations_.end()) {
+    content::NavigationHandle* navigation_handle = *it;
+    if (navigation_handle && navigation_handle->GetWebContents() == contents) {
+      loading_contents_ = navigation_handle->GetWebContents();
+      navigation_handle->Resume();
+      pending_navigations_.erase(it);
+      break;
+    }
+    it++;
+  }
+}
+
 }  // namespace resource_coordinator