Add resource_coordinator::TabLifecycleUnit.

A TabLifecycleUnit represents a tab.

The implementation will be in a separate class (TabLifecyleUnitImpl)
because we want to expose only part of the it outside of
chrome/browser/resource_coordinator/.

E.g. the extensions system is allowed call:

TabLifecycleUnit::FromWebContents(contents)->Discard(condition);

but we don't want it to change the TabStripModel associated with
a tab (TabLifecycleUnitImpl::set_tab_strip_model()).

Bug: 775644
Change-Id: Idf2ad85bf2969871be1dc09eb1eb3776bc922959
Reviewed-on: https://chromium-review.googlesource.com/774979Reviewed-by: Chris Hamilton <chrisha@chromium.org>
Commit-Queue: François Doray <fdoray@chromium.org>
Cr-Commit-Position: refs/heads/master@{#518410}

chrome/browser/BUILD.gn

@@ -2557,6 +2557,8 @@ split_static_library("browser") {
       "resource_coordinator/discard_condition.h",
       "resource_coordinator/lifecycle_unit.cc",
       "resource_coordinator/lifecycle_unit.h",
+      "resource_coordinator/tab_lifecycle_unit.cc",
+      "resource_coordinator/tab_lifecycle_unit.h",
       "resource_coordinator/tab_lifetime_observer.cc",
       "resource_coordinator/tab_lifetime_observer.h",
       "resource_coordinator/tab_manager.cc",

chrome/browser/resource_coordinator/tab_lifecycle_unit.cc

+// 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/tab_lifecycle_unit.h"
+
+#include "base/macros.h"
+#include "content/public/browser/web_contents_user_data.h"
+
+namespace resource_coordinator {
+
+namespace {
+
+class TabLifecycleUnitHolder
+    : public content::WebContentsUserData<TabLifecycleUnitHolder> {
+ public:
+  explicit TabLifecycleUnitHolder(content::WebContents*) {}
+  TabLifecycleUnit* tab_lifecycle_unit() const { return tab_lifecycle_unit_; }
+  void set_tab_lifecycle_unit(TabLifecycleUnit* tab_lifecycle_unit) {
+    tab_lifecycle_unit_ = tab_lifecycle_unit;
+  }
+
+ private:
+  TabLifecycleUnit* tab_lifecycle_unit_ = nullptr;
+
+  DISALLOW_COPY_AND_ASSIGN(TabLifecycleUnitHolder);
+};
+
+}  // namespace
+
+// static
+TabLifecycleUnit* TabLifecycleUnit::FromWebContents(
+    content::WebContents* web_contents) {
+  TabLifecycleUnitHolder* holder =
+      TabLifecycleUnitHolder::FromWebContents(web_contents);
+  return holder ? holder->tab_lifecycle_unit() : nullptr;
+}
+
+// static
+void TabLifecycleUnit::SetForWebContents(content::WebContents* web_contents,
+                                         TabLifecycleUnit* tab_lifecycle_unit) {
+  TabLifecycleUnitHolder::CreateForWebContents(web_contents);
+  TabLifecycleUnitHolder::FromWebContents(web_contents)
+      ->set_tab_lifecycle_unit(tab_lifecycle_unit);
+}
+
+}  // namespace resource_coordinator
+
+DEFINE_WEB_CONTENTS_USER_DATA_KEY(resource_coordinator::TabLifecycleUnitHolder);

chrome/browser/resource_coordinator/tab_lifecycle_unit.h

+// 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.
+
+#ifndef CHROME_BROWSER_RESOURCE_COORDINATOR_TAB_LIFECYCLE_UNIT_H_
+#define CHROME_BROWSER_RESOURCE_COORDINATOR_TAB_LIFECYCLE_UNIT_H_
+
+#include "chrome/browser/resource_coordinator/lifecycle_unit.h"
+
+namespace content {
+class RenderProcessHost;
+class WebContents;
+}  // namespace content
+
+namespace resource_coordinator {
+
+// Represents a tab.
+class TabLifecycleUnit : public LifecycleUnit {
+ public:
+  // Returns the TabLifecycleUnit associated with |web_contents|, or nullptr if
+  // the WebContents is not associated with a tab.
+  static TabLifecycleUnit* FromWebContents(content::WebContents* web_contents);
+
+  // Returns the WebContents associated with this tab.
+  virtual content::WebContents* GetWebContents() const = 0;
+
+  // Returns the RenderProcessHost associated with this tab.
+  virtual content::RenderProcessHost* GetRenderProcessHost() const = 0;
+
+  // Returns true if the tab is playing audio, has played audio recently, is
+  // accessing the microphone, is accessing the camera or is being mirrored.
+  virtual bool IsMediaTab() const = 0;
+
+  // Returns true if this tab can be automatically discarded.
+  virtual bool IsAutoDiscardable() const = 0;
+
+  // Allows/disallows this tab to be automatically discarded.
+  virtual void SetAutoDiscardable(bool auto_discardable) = 0;
+
+ protected:
+  // Sets the TabLifecycleUnit associated with |web_contents|.
+  static void SetForWebContents(content::WebContents* web_contents,
+                                TabLifecycleUnit* tab_lifecycle_unit);
+};
+
+}  // namespace resource_coordinator
+
+#endif  // CHROME_BROWSER_RESOURCE_COORDINATOR_TAB_LIFECYCLE_UNIT_H_

chrome/browser/resource_coordinator/tab_lifecycle_unit_unittest.cc

+// 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/tab_lifecycle_unit.h"
+
+#include "base/macros.h"
+#include "chrome/test/base/chrome_render_view_host_test_harness.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace resource_coordinator {
+
+namespace {
+
+class DummyTabLifecycleUnit : public TabLifecycleUnit {
+ public:
+  explicit DummyTabLifecycleUnit(content::WebContents* contents)
+      : contents_(contents) {
+    TabLifecycleUnit::SetForWebContents(contents_, this);
+  }
+
+  ~DummyTabLifecycleUnit() override {
+    TabLifecycleUnit::SetForWebContents(contents_, nullptr);
+  }
+
+  // TabLifecycleUnit:
+  content::WebContents* GetWebContents() const override { return nullptr; }
+  content::RenderProcessHost* GetRenderProcessHost() const override {
+    return nullptr;
+  }
+  bool IsMediaTab() const override { return false; }
+  bool IsAutoDiscardable() const override { return false; }
+  void SetAutoDiscardable(bool) override {}
+
+  // LifecycleUnit:
+  base::string16 GetTitle() const override { return base::string16(); }
+  std::string GetIconURL() const override { return std::string(); }
+  SortKey GetSortKey() const override { return SortKey(); }
+  State GetState() const override { return State::LOADED; }
+  int GetEstimatedMemoryFreedOnDiscardKB() const override { return 0; }
+  bool CanDiscard(DiscardCondition) const override { return false; }
+  bool Discard(DiscardCondition) override { return false; }
+
+ private:
+  content::WebContents* const contents_;
+
+  DISALLOW_COPY_AND_ASSIGN(DummyTabLifecycleUnit);
+};
+
+}  // namespace
+
+using TabLifecycleUnitTest = ChromeRenderViewHostTestHarness;
+
+TEST_F(TabLifecycleUnitTest, FromWebContentsNullByDefault) {
+  EXPECT_FALSE(TabLifecycleUnit::FromWebContents(web_contents()));
+}
+
+TEST_F(TabLifecycleUnitTest, SetForWebContents) {
+  {
+    DummyTabLifecycleUnit tab_lifecycle_unit(web_contents());
+    EXPECT_EQ(&tab_lifecycle_unit,
+              TabLifecycleUnit::FromWebContents(web_contents()));
+  }
+  EXPECT_FALSE(TabLifecycleUnit::FromWebContents(web_contents()));
+  {
+    DummyTabLifecycleUnit tab_lifecycle_unit(web_contents());
+    EXPECT_EQ(&tab_lifecycle_unit,
+              TabLifecycleUnit::FromWebContents(web_contents()));
+  }
+  EXPECT_FALSE(TabLifecycleUnit::FromWebContents(web_contents()));
+}
+
+}  // namespace resource_coordinator

chrome/test/BUILD.gn

@@ -2720,6 +2720,7 @@ test("unit_tests") {
       "../browser/page_load_metrics/observers/session_restore_page_load_metrics_observer_unittest.cc",
       "../browser/resource_coordinator/background_tab_navigation_throttle_unittest.cc",
       "../browser/resource_coordinator/lifecycle_unit_unittest.cc",
+      "../browser/resource_coordinator/tab_lifecycle_unit_unittest.cc",
       "../browser/resource_coordinator/tab_manager_delegate_chromeos_unittest.cc",
       "../browser/resource_coordinator/tab_manager_stats_collector_unittest.cc",
       "../browser/resource_coordinator/tab_manager_unittest.cc",