Revert of New Task Manager - Phase 1.3.2: Implement Tab Contents Task Providing (patchset #3 id:40001 of https://codereview.chromium.org/1212663002/)

Reason for revert:
Reverting this because it makes the following test flaky: BackgroundContentsTagTest.PreExistingTasksAreProvided

See example of failure here: https://commondatastorage.googleapis.com/chromium-build-logs/logs/2015/7/ahVzfmNocm9taXVtLWJ1aWxkLWxvZ3NynAELEgVCdWlsZCJ7MSAtIGh0dHA6Ly9idWlsZC5jaHJvbWl1bS5vcmcvcC9jaHJvbWl1bS5jaHJvbWl1bW9zL2pzb24gLSBMaW51eCBDaHJvbWl1bU9TIFRlc3RzIChkYmcpKDEpIC0gNDM4OCAtIDE0MzYzOTkyODIgLSAxNDM2NDAwNzQxDAsSCUJ1aWxkU3RlcBiAgICAgOSVCQw

Error message:
../../chrome/browser/task_management/providers/web_contents/background_contents_tag_browsertest.cc:117: Failure
Value of: task->title()
  Actual: Tab: about:blank
Expected: GetBackgroundTaskExpectedName(extension)
Which is: Background Page: app_process_background_instances

Original issue's description:
> New Task Manager - Phase 1.3.2: Implement Tab Contents Task Providing
>
> Part 3 of 3: Implementing a task-manager representation of WebContents
> owned
> by the TabStripModel.
>
> R=nick@chromium.org
> BUG=470990
> TEST=browser_tests --gtest_filter=TabContentsTagTest.*
>
> Committed: https://crrev.com/543b07d4fb0b807639e8d29a0249794f240db091
> Cr-Commit-Position: refs/heads/master@{#337936}

TBR=nick@chromium.org,gavinp@chromium.org,pkasting@chromium.org,avi@chromium.org,davidben@chromium.org,afakhry@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=470990

Review URL: https://codereview.chromium.org/1229923002

Cr-Commit-Position: refs/heads/master@{#338051}

22 files changed, 169 insertions, 609 deletions

diff --git a/chrome/browser/prerender/prerender_browsertest.cc b/chrome/browser/prerender/prerender_browsertest.cc
index 9c83077..c08cfaa 100644
--- a/chrome/browser/prerender/prerender_browsertest.cc
+++ b/chrome/browser/prerender/prerender_browsertest.cc
@@ -49,8 +49,9 @@
 #include "chrome/browser/safe_browsing/safe_browsing_service.h"
 #include "chrome/browser/safe_browsing/safe_browsing_util.h"
 #include "chrome/browser/safe_browsing/test_database_manager.h"
+#include "chrome/browser/task_management/providers/task_provider_observer.h"
 #include "chrome/browser/task_management/providers/web_contents/web_contents_tags_manager.h"
-#include "chrome/browser/task_management/task_management_browsertest_util.h"
+#include "chrome/browser/task_management/providers/web_contents/web_contents_task_provider.h"
 #include "chrome/browser/task_manager/task_manager.h"
 #include "chrome/browser/task_manager/task_manager_browsertest_util.h"
 #include "chrome/browser/ui/browser.h"
@@ -4087,58 +4088,92 @@ IN_PROC_BROWSER_TEST_F(PrerenderBrowserTestWithNaCl,
 
 namespace {
 
-base::string16 GetPrerenderTitlePrefix() {
-  return l10n_util::GetStringFUTF16(IDS_TASK_MANAGER_PRERENDER_PREFIX,
-                                    base::string16());
-}
+// Defines a test class for testing that will act as a mock task manager.
+class MockTaskManager : public task_management::TaskProviderObserver {
+ public:
+  MockTaskManager() {}
+  ~MockTaskManager() override {}
 
-const std::set<task_management::WebContentsTag*>& GetTrackedTags() {
-  return task_management::WebContentsTagsManager::GetInstance()->
-      tracked_tags();
-}
+  // task_management::Task_providerObserver:
+  void TaskAdded(task_management::Task* task) override {
+    EXPECT_FALSE(ContainsKey(provided_tasks_, task));
+    provided_tasks_.insert(task);
+  }
+
+  void TaskRemoved(task_management::Task* task) override {
+    EXPECT_TRUE(ContainsKey(provided_tasks_, task));
+    provided_tasks_.erase(task);
+  }
+
+  base::string16 GetPrerenderTitlePrefix() const {
+    return l10n_util::GetStringFUTF16(IDS_TASK_MANAGER_PRERENDER_PREFIX,
+                                      base::string16());
+  }
+
+  const std::set<task_management::WebContentsTag*>& tracked_tags() const {
+    return task_management::WebContentsTagsManager::GetInstance()->
+        tracked_tags();
+  }
+
+  const std::set<task_management::Task*>& provided_tasks() const {
+    return provided_tasks_;
+  }
+
+ private:
+  std::set<task_management::Task*> provided_tasks_;
+
+  DISALLOW_COPY_AND_ASSIGN(MockTaskManager);
+};
 
 // Tests the correct recording of tags for the prerender WebContents.
 IN_PROC_BROWSER_TEST_F(PrerenderBrowserTest, TaskManagementTagsBasic) {
-  // Browser tests start with a single tab.
-  EXPECT_EQ(1U, GetTrackedTags().size());
+  MockTaskManager task_manager;
+  EXPECT_TRUE(task_manager.tracked_tags().empty());
 
   // Start prerendering a page and make sure it's correctly tagged.
   PrerenderTestURL("files/prerender/prerender_page.html", FINAL_STATUS_USED, 1);
-  EXPECT_EQ(2U, GetTrackedTags().size());
+  EXPECT_FALSE(task_manager.tracked_tags().empty());
+
+  // TODO(afakhry): Once we start tagging the tab contents the below tests
+  // must be changed.
+  EXPECT_EQ(1U, task_manager.tracked_tags().size());
 
   // Swap in the prerendered content and make sure its tag is removed.
   NavigateToDestURL();
-  EXPECT_EQ(1U, GetTrackedTags().size());
+  EXPECT_TRUE(task_manager.tracked_tags().empty());
 }
 
 // Tests that the task manager will be provided by tasks that correspond to
 // prerendered WebContents.
 IN_PROC_BROWSER_TEST_F(PrerenderBrowserTest, TaskManagementTasksProvided) {
-  task_management::MockWebContentsTaskManager task_manager;
-  // Browser tests start with a single tab.
-  EXPECT_EQ(1U, GetTrackedTags().size());
+  MockTaskManager task_manager;
+  EXPECT_TRUE(task_manager.tracked_tags().empty());
 
-  task_manager.StartObserving();
+  task_management::WebContentsTaskProvider provider;
+  provider.SetObserver(&task_manager);
 
-  // The pre-existing tab is provided.
-  EXPECT_EQ(1U, task_manager.tasks().size());
+  // Still empty, no pre-existing tasks.
+  EXPECT_TRUE(task_manager.provided_tasks().empty());
 
   // Start prerendering a page.
   PrerenderTestURL("files/prerender/prerender_page.html", FINAL_STATUS_USED, 1);
+  EXPECT_FALSE(task_manager.tracked_tags().empty());
 
-  EXPECT_EQ(2U, GetTrackedTags().size());
-  ASSERT_EQ(2U, task_manager.tasks().size());
+  // TODO(afakhry): The below may not be true after we support more tags.
+  EXPECT_EQ(1U, task_manager.tracked_tags().size());
+  ASSERT_EQ(1U, task_manager.provided_tasks().size());
 
-  const task_management::Task* task = task_manager.tasks().back();
+  const task_management::Task* task = *task_manager.provided_tasks().begin();
   EXPECT_EQ(task_management::Task::RENDERER, task->GetType());
   const base::string16 title = task->title();
-  const base::string16 expected_prefix = GetPrerenderTitlePrefix();
+  const base::string16 expected_prefix = task_manager.GetPrerenderTitlePrefix();
   EXPECT_TRUE(base::StartsWith(title,
                                expected_prefix,
                                base::CompareCase::INSENSITIVE_ASCII));
 
   NavigateToDestURL();
-  EXPECT_EQ(1U, task_manager.tasks().size());
+  // TODO(afakhry): The below may not be true after we support more tags.
+  EXPECT_TRUE(task_manager.provided_tasks().empty());
 }
 
 }  // namespace
diff --git a/chrome/browser/task_management/providers/web_contents/background_contents_tag_browsertest.cc b/chrome/browser/task_management/providers/web_contents/background_contents_tag_browsertest.cc
index ec17c4d..c70fa3b 100644
--- a/chrome/browser/task_management/providers/web_contents/background_contents_tag_browsertest.cc
+++ b/chrome/browser/task_management/providers/web_contents/background_contents_tag_browsertest.cc
@@ -4,8 +4,9 @@
 
 #include "base/strings/utf_string_conversions.h"
 #include "chrome/browser/extensions/extension_browsertest.h"
+#include "chrome/browser/task_management/providers/task_provider_observer.h"
 #include "chrome/browser/task_management/providers/web_contents/web_contents_tags_manager.h"
-#include "chrome/browser/task_management/task_management_browsertest_util.h"
+#include "chrome/browser/task_management/providers/web_contents/web_contents_task_provider.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/grit/generated_resources.h"
 #include "extensions/common/switches.h"
@@ -17,7 +18,9 @@ namespace task_management {
 // properly and the TagsManager records these tags. It is also used to test that
 // the WebContentsTaskProvider will be able to provide the appropriate
 // BackgroundContentsTask.
-class BackgroundContentsTagTest : public ExtensionBrowserTest {
+class BackgroundContentsTagTest
+    : public ExtensionBrowserTest,
+      public TaskProviderObserver {
  public:
   BackgroundContentsTagTest() {}
   ~BackgroundContentsTagTest() override {}
@@ -34,92 +37,109 @@ class BackgroundContentsTagTest : public ExtensionBrowserTest {
                                       base::UTF8ToUTF16(extension->name()));
   }
 
+  // task_management::Task_providerObserver:
+  void TaskAdded(Task* task) override {
+    CHECK(task);
+    ASSERT_FALSE(provided_tasks_.count(task));
+    provided_tasks_.insert(task);
+  }
+
+  void TaskRemoved(Task* task) override {
+    CHECK(task);
+    ASSERT_TRUE(provided_tasks_.count(task));
+    provided_tasks_.erase(task);
+  }
+
   WebContentsTagsManager* tags_manager() const {
     return WebContentsTagsManager::GetInstance();
   }
 
+  const std::set<Task*>& provided_tasks() const { return provided_tasks_; }
+
  protected:
-  // ExtensionBrowserTest:
+  // ExtensionApiTest:
   void SetUpCommandLine(base::CommandLine* command_line) override {
     // Pass flags to make testing apps easier.
     ExtensionBrowserTest::SetUpCommandLine(command_line);
     test_data_dir_ = test_data_dir_.AppendASCII("api_test");
-    command_line->AppendSwitch(switches::kDisableRendererBackgrounding);
-    command_line->AppendSwitch(switches::kDisablePopupBlocking);
-    command_line->AppendSwitch(extensions::switches::kAllowHTTPBackgroundPage);
+    base::CommandLine::ForCurrentProcess()->AppendSwitch(
+        switches::kDisablePopupBlocking);
+    base::CommandLine::ForCurrentProcess()->AppendSwitch(
+        extensions::switches::kAllowHTTPBackgroundPage);
   }
 
  private:
+  std::set<Task*> provided_tasks_;
+
   DISALLOW_COPY_AND_ASSIGN(BackgroundContentsTagTest);
 };
 
 // Tests that loading an extension that has a background contents will result in
 // the tags manager recording a WebContentsTag.
 IN_PROC_BROWSER_TEST_F(BackgroundContentsTagTest, TagsManagerRecordsATag) {
-  // Browser tests start with only one tab available.
-  EXPECT_EQ(1U, tags_manager()->tracked_tags().size());
-  auto extension = LoadBackgroundExtension();
-  ASSERT_NE(nullptr, extension);
-  EXPECT_EQ(2U, tags_manager()->tracked_tags().size());
-
-  // Unload the extension.
-  UnloadExtension(extension->id());
+  EXPECT_TRUE(provided_tasks().empty());
+  EXPECT_TRUE(tags_manager()->tracked_tags().empty());
+  EXPECT_TRUE(LoadBackgroundExtension());
+  EXPECT_FALSE(tags_manager()->tracked_tags().empty());
   EXPECT_EQ(1U, tags_manager()->tracked_tags().size());
+  EXPECT_TRUE(provided_tasks().empty());
 }
 
 // Tests that background contents creation while the provider is being observed
 // will also provide tasks.
 IN_PROC_BROWSER_TEST_F(BackgroundContentsTagTest, TasksProvidedWhileObserving) {
-  MockWebContentsTaskManager task_manager;
-  EXPECT_TRUE(task_manager.tasks().empty());
-  // Browser tests start with only one tab available.
-  EXPECT_EQ(1U, tags_manager()->tracked_tags().size());
+  EXPECT_TRUE(provided_tasks().empty());
+  EXPECT_TRUE(tags_manager()->tracked_tags().empty());
 
-  task_manager.StartObserving();
+  WebContentsTaskProvider provider;
+  provider.SetObserver(this);
 
-  // The pre-existing tab is provided.
-  EXPECT_EQ(1U, task_manager.tasks().size());
+  // Still empty, no pre-existing tasks.
+  EXPECT_TRUE(provided_tasks().empty());
 
   auto extension = LoadBackgroundExtension();
   ASSERT_NE(nullptr, extension);
-  EXPECT_EQ(2U, tags_manager()->tracked_tags().size());
-  EXPECT_EQ(2U, task_manager.tasks().size());
+  EXPECT_FALSE(tags_manager()->tracked_tags().empty());
+  EXPECT_EQ(1U, tags_manager()->tracked_tags().size());
+  EXPECT_FALSE(provided_tasks().empty());
+  EXPECT_EQ(1U, provided_tasks().size());
 
-  // Now check the newly provided task.
-  const Task* task = task_manager.tasks().back();
+  // Now check the provided task.
+  const Task* task = *provided_tasks().begin();
   EXPECT_EQ(Task::RENDERER, task->GetType());
   EXPECT_EQ(GetBackgroundTaskExpectedName(extension), task->title());
 
   // Unload the extension.
   UnloadExtension(extension->id());
-  EXPECT_EQ(1U, task_manager.tasks().size());
-  EXPECT_EQ(1U, tags_manager()->tracked_tags().size());
+  EXPECT_TRUE(provided_tasks().empty());
+  EXPECT_TRUE(tags_manager()->tracked_tags().empty());
 }
 
 // Tests providing a pre-existing background task to the observing operation.
 IN_PROC_BROWSER_TEST_F(BackgroundContentsTagTest, PreExistingTasksAreProvided) {
-  MockWebContentsTaskManager task_manager;
-  EXPECT_TRUE(task_manager.tasks().empty());
-  // Browser tests start with only one tab available.
-  EXPECT_EQ(1U, tags_manager()->tracked_tags().size());
+  EXPECT_TRUE(provided_tasks().empty());
+  EXPECT_TRUE(tags_manager()->tracked_tags().empty());
   auto extension = LoadBackgroundExtension();
   ASSERT_NE(nullptr, extension);
-  EXPECT_EQ(2U, tags_manager()->tracked_tags().size());
+  EXPECT_FALSE(tags_manager()->tracked_tags().empty());
+  EXPECT_EQ(1U, tags_manager()->tracked_tags().size());
 
-  task_manager.StartObserving();
+  WebContentsTaskProvider provider;
+  provider.SetObserver(this);
 
   // Pre-existing task will be provided to us.
-  EXPECT_EQ(2U, task_manager.tasks().size());
+  EXPECT_FALSE(provided_tasks().empty());
+  EXPECT_EQ(1U, provided_tasks().size());
 
   // Now check the provided task.
-  const Task* task = task_manager.tasks().back();
+  const Task* task = *provided_tasks().begin();
   EXPECT_EQ(Task::RENDERER, task->GetType());
   EXPECT_EQ(GetBackgroundTaskExpectedName(extension), task->title());
 
   // Unload the extension.
   UnloadExtension(extension->id());
-  EXPECT_EQ(1U, task_manager.tasks().size());
-  EXPECT_EQ(1U, tags_manager()->tracked_tags().size());
+  EXPECT_TRUE(provided_tasks().empty());
+  EXPECT_TRUE(tags_manager()->tracked_tags().empty());
 }
 
 }  // namespace task_management
diff --git a/chrome/browser/task_management/providers/web_contents/devtools_tag_browsertest.cc b/chrome/browser/task_management/providers/web_contents/devtools_tag_browsertest.cc
index c009d52..68fdb7d 100644
--- a/chrome/browser/task_management/providers/web_contents/devtools_tag_browsertest.cc
+++ b/chrome/browser/task_management/providers/web_contents/devtools_tag_browsertest.cc
@@ -3,8 +3,9 @@
 // found in the LICENSE file.
 
 #include "chrome/browser/devtools/devtools_window_testing.h"
+#include "chrome/browser/task_management/providers/task_provider_observer.h"
 #include "chrome/browser/task_management/providers/web_contents/web_contents_tags_manager.h"
-#include "chrome/browser/task_management/task_management_browsertest_util.h"
+#include "chrome/browser/task_management/providers/web_contents/web_contents_task_provider.h"
 #include "chrome/browser/ui/browser.h"
 #include "chrome/browser/ui/tabs/tab_strip_model.h"
 #include "chrome/test/base/in_process_browser_test.h"
@@ -23,10 +24,13 @@ const char kTestPage2[] = "files/devtools/navigate_back.html";
 // properly by a DevToolsTag and that the TagsManager records these tags. It
 // will also test that the WebContentsTaskProvider will be able to provide the
 // appropriate DevToolsTask.
-class DevToolsTagTest : public InProcessBrowserTest {
+class DevToolsTagTest
+    : public InProcessBrowserTest,
+      public TaskProviderObserver {
  public:
   DevToolsTagTest()
-      : devtools_window_(nullptr) {
+      : devtools_window_(nullptr),
+        provided_tasks_() {
     CHECK(test_server()->Start());
   }
 
@@ -46,12 +50,28 @@ class DevToolsTagTest : public InProcessBrowserTest {
     DevToolsWindowTesting::CloseDevToolsWindowSync(devtools_window_);
   }
 
+  // task_management::Task_providerObserver:
+  void TaskAdded(Task* task) override {
+    CHECK(task);
+    ASSERT_FALSE(provided_tasks_.count(task));
+    provided_tasks_.insert(task);
+  }
+
+  void TaskRemoved(Task* task) override {
+    CHECK(task);
+    ASSERT_TRUE(provided_tasks_.count(task));
+    provided_tasks_.erase(task);
+  }
+
   WebContentsTagsManager* tags_manager() const {
     return WebContentsTagsManager::GetInstance();
   }
 
+  const std::set<Task*>& provided_tasks() const { return provided_tasks_; }
+
  private:
   DevToolsWindow* devtools_window_;
+  std::set<Task*> provided_tasks_;
 
   DISALLOW_COPY_AND_ASSIGN(DevToolsTagTest);
 };
@@ -59,48 +79,52 @@ class DevToolsTagTest : public InProcessBrowserTest {
 // Tests that opening a DevToolsWindow will result in tagging its main
 // WebContents and that tag will be recorded by the TagsManager.
 IN_PROC_BROWSER_TEST_F(DevToolsTagTest, TagsManagerRecordsATag) {
-  // Browser tests start with a single tab.
-  EXPECT_EQ(1U, tags_manager()->tracked_tags().size());
+  EXPECT_TRUE(tags_manager()->tracked_tags().empty());
 
-  // Navigating the same tab to the test page won't change the number of tracked
-  // tags. No devtools yet.
+  // Loading a page will not result in tagging its WebContents.
+  // TODO(afakhry): Once we start tagging the tab contents, this will change.
+  // Fix it.
   LoadTestPage(kTestPage1);
-  EXPECT_EQ(1U, tags_manager()->tracked_tags().size());
+  EXPECT_TRUE(tags_manager()->tracked_tags().empty());
 
   // Test both docked and undocked devtools.
   OpenDevToolsWindow(true);
-  EXPECT_EQ(2U, tags_manager()->tracked_tags().size());
-  CloseDevToolsWindow();
+  EXPECT_FALSE(tags_manager()->tracked_tags().empty());
   EXPECT_EQ(1U, tags_manager()->tracked_tags().size());
+  CloseDevToolsWindow();
+  EXPECT_TRUE(tags_manager()->tracked_tags().empty());
 
   // For the undocked devtools there will be two tags one for the main contents
   // and one for the toolbox contents
   OpenDevToolsWindow(false);
-  EXPECT_EQ(3U, tags_manager()->tracked_tags().size());
+  EXPECT_FALSE(tags_manager()->tracked_tags().empty());
+  EXPECT_EQ(2U, tags_manager()->tracked_tags().size());
   CloseDevToolsWindow();
-  EXPECT_EQ(1U, tags_manager()->tracked_tags().size());
+  EXPECT_TRUE(tags_manager()->tracked_tags().empty());
 }
 
 IN_PROC_BROWSER_TEST_F(DevToolsTagTest, DevToolsTaskIsProvided) {
-  MockWebContentsTaskManager task_manager;
-  EXPECT_TRUE(task_manager.tasks().empty());
-  // Browser tests start with a single tab.
-  EXPECT_EQ(1U, tags_manager()->tracked_tags().size());
+  EXPECT_TRUE(provided_tasks().empty());
+  EXPECT_TRUE(tags_manager()->tracked_tags().empty());
 
-  task_manager.StartObserving();
+  WebContentsTaskProvider provider;
+  provider.SetObserver(this);
 
-  // The pre-existing tab is provided.
-  EXPECT_EQ(1U, task_manager.tasks().size());
+  // Still empty, no pre-existing tasks.
+  EXPECT_TRUE(provided_tasks().empty());
 
   LoadTestPage(kTestPage1);
-  EXPECT_EQ(1U, tags_manager()->tracked_tags().size());
-  EXPECT_EQ(1U, task_manager.tasks().size());
+  // TODO(afakhry): This will change soon.
+  EXPECT_TRUE(provided_tasks().empty());
+  EXPECT_TRUE(tags_manager()->tracked_tags().empty());
 
   OpenDevToolsWindow(true);
-  EXPECT_EQ(2U, tags_manager()->tracked_tags().size());
-  EXPECT_EQ(2U, task_manager.tasks().size());
+  EXPECT_FALSE(tags_manager()->tracked_tags().empty());
+  EXPECT_EQ(1U, tags_manager()->tracked_tags().size());
+  EXPECT_FALSE(provided_tasks().empty());
+  EXPECT_EQ(1U, provided_tasks().size());
 
-  const Task* task = task_manager.tasks().back();
+  const Task* task = *provided_tasks().begin();
   EXPECT_EQ(Task::RENDERER, task->GetType());
 
   // Navigating to a new page will not change the title of the devtools main
@@ -111,8 +135,8 @@ IN_PROC_BROWSER_TEST_F(DevToolsTagTest, DevToolsTaskIsProvided) {
   EXPECT_EQ(title1, title2);
 
   CloseDevToolsWindow();
-  EXPECT_EQ(1U, tags_manager()->tracked_tags().size());
-  EXPECT_EQ(1U, task_manager.tasks().size());
+  EXPECT_TRUE(provided_tasks().empty());
+  EXPECT_TRUE(tags_manager()->tracked_tags().empty());
 }
 
 }  // namespace task_management
diff --git a/chrome/browser/task_management/providers/web_contents/prerender_tag.cc b/chrome/browser/task_management/providers/web_contents/prerender_tag.cc
index 499756c..6e6ae3d 100644
--- a/chrome/browser/task_management/providers/web_contents/prerender_tag.cc
+++ b/chrome/browser/task_management/providers/web_contents/prerender_tag.cc
@@ -3,6 +3,7 @@
 // found in the LICENSE file.
 
 #include "chrome/browser/task_management/providers/web_contents/prerender_tag.h"
+#include "chrome/browser/task_management/providers/web_contents/web_contents_tags_manager.h"
 
 namespace task_management {
 
diff --git a/chrome/browser/task_management/providers/web_contents/renderer_task.cc b/chrome/browser/task_management/providers/web_contents/renderer_task.cc
index 32acdb1..33cef0e 100644
--- a/chrome/browser/task_management/providers/web_contents/renderer_task.cc
+++ b/chrome/browser/task_management/providers/web_contents/renderer_task.cc
@@ -11,11 +11,9 @@
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/profiles/profile_info_cache.h"
 #include "chrome/browser/profiles/profile_manager.h"
-#include "chrome/grit/generated_resources.h"
 #include "content/public/browser/render_process_host.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/browser/web_contents_delegate.h"
-#include "ui/base/l10n/l10n_util.h"
 
 namespace task_management {
 
@@ -143,29 +141,4 @@ const gfx::ImageSkia* RendererTask::GetFaviconFromWebContents(
   return image.ToImageSkia();
 }
 
-// static
-const base::string16 RendererTask::PrefixRendererTitle(
-    const base::string16& title,
-    bool is_app,
-    bool is_extension,
-    bool is_incognito) {
-  int message_id = IDS_TASK_MANAGER_TAB_PREFIX;
-
-  if (is_incognito && !is_app && !is_extension) {
-    message_id = IDS_TASK_MANAGER_TAB_INCOGNITO_PREFIX;
-  } else if (is_app) {
-    if (is_incognito)
-      message_id = IDS_TASK_MANAGER_APP_INCOGNITO_PREFIX;
-    else
-      message_id = IDS_TASK_MANAGER_APP_PREFIX;
-  } else if (is_extension) {
-    if (is_incognito)
-      message_id = IDS_TASK_MANAGER_EXTENSION_INCOGNITO_PREFIX;
-    else
-      message_id = IDS_TASK_MANAGER_EXTENSION_PREFIX;
-  }
-
-  return l10n_util::GetStringFUTF16(message_id, title);
-}
-
 }  // namespace task_management
diff --git a/chrome/browser/task_management/providers/web_contents/renderer_task.h b/chrome/browser/task_management/providers/web_contents/renderer_task.h
index ed88fd0..5fcb445 100644
--- a/chrome/browser/task_management/providers/web_contents/renderer_task.h
+++ b/chrome/browser/task_management/providers/web_contents/renderer_task.h
@@ -55,13 +55,6 @@ class RendererTask : public Task {
   static const gfx::ImageSkia* GetFaviconFromWebContents(
       content::WebContents* web_contents);
 
-  // Prefixes the given renderer |title| with the appropriate string based on
-  // whether it's an app, an extension, or incognito.
-  static const base::string16 PrefixRendererTitle(const base::string16& title,
-                                                  bool is_app,
-                                                  bool is_extension,
-                                                  bool is_incognito);
-
   content::WebContents* web_contents() const { return web_contents_; }
 
  private:
diff --git a/chrome/browser/task_management/providers/web_contents/tab_contents_tag.cc b/chrome/browser/task_management/providers/web_contents/tab_contents_tag.cc
deleted file mode 100644
index 9ac341c..0000000
--- a/chrome/browser/task_management/providers/web_contents/tab_contents_tag.cc
+++ /dev/null
@@ -1,20 +0,0 @@
-// Copyright 2015 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/task_management/providers/web_contents/tab_contents_tag.h"
-
-namespace task_management {
-
-TabContentsTask* TabContentsTag::CreateTask() const {
-  return new TabContentsTask(web_contents());
-}
-
-TabContentsTag::TabContentsTag(content::WebContents* web_contents)
-    : WebContentsTag(web_contents) {
-}
-
-TabContentsTag::~TabContentsTag() {
-}
-
-}  // namespace task_management
diff --git a/chrome/browser/task_management/providers/web_contents/tab_contents_tag.h b/chrome/browser/task_management/providers/web_contents/tab_contents_tag.h
deleted file mode 100644
index 777a62f..0000000
--- a/chrome/browser/task_management/providers/web_contents/tab_contents_tag.h
+++ /dev/null
@@ -1,30 +0,0 @@
-// Copyright 2015 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_TASK_MANAGEMENT_PROVIDERS_WEB_CONTENTS_TAB_CONTENTS_TAG_H_
-#define CHROME_BROWSER_TASK_MANAGEMENT_PROVIDERS_WEB_CONTENTS_TAB_CONTENTS_TAG_H_
-
-#include "chrome/browser/task_management/providers/web_contents/tab_contents_task.h"
-#include "chrome/browser/task_management/providers/web_contents/web_contents_tag.h"
-
-namespace task_management {
-
-// Defines a concrete UserData type for WebContents owned by the TabStripModel.
-class TabContentsTag : public WebContentsTag {
- public:
-  // task_management::WebContentsTag:
-  TabContentsTask* CreateTask() const override;
-
- private:
-  friend class WebContentsTags;
-
-  explicit TabContentsTag(content::WebContents* web_contents);
-  ~TabContentsTag() override;
-
-  DISALLOW_COPY_AND_ASSIGN(TabContentsTag);
-};
-
-}  // namespace task_management
-
-#endif  // CHROME_BROWSER_TASK_MANAGEMENT_PROVIDERS_WEB_CONTENTS_TAB_CONTENTS_TAG_H_
diff --git a/chrome/browser/task_management/providers/web_contents/tab_contents_tag_browsertest.cc b/chrome/browser/task_management/providers/web_contents/tab_contents_tag_browsertest.cc
deleted file mode 100644
index 43f6aa0..0000000
--- a/chrome/browser/task_management/providers/web_contents/tab_contents_tag_browsertest.cc
+++ /dev/null
@@ -1,200 +0,0 @@
-// Copyright 2015 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 "base/strings/utf_string_conversions.h"
-#include "chrome/browser/task_management/providers/web_contents/web_contents_tags_manager.h"
-#include "chrome/browser/task_management/task_management_browsertest_util.h"
-#include "chrome/browser/ui/browser.h"
-#include "chrome/browser/ui/tabs/tab_strip_model.h"
-#include "chrome/grit/generated_resources.h"
-#include "chrome/test/base/in_process_browser_test.h"
-#include "chrome/test/base/ui_test_utils.h"
-#include "net/test/embedded_test_server/embedded_test_server.h"
-#include "ui/base/l10n/l10n_util.h"
-#include "ui/base/page_transition_types.h"
-
-namespace task_management {
-
-namespace {
-
-// Defines a test page file path along with its expected task manager reported
-// values.
-struct TestPageData {
-  const char* page_file;
-  const char* title;
-  Task::Type task_type;
-  int expected_prefix_message;
-};
-
-// The below test files are available in src/chrome/test/data/
-// TODO(afakhry): Add more test pages here as needed (e.g. pages that are hosted
-// in the tabs as apps or extensions).
-const TestPageData kTestPages[] = {
-    {
-        "/title1.html",
-        "",
-        Task::RENDERER,
-        IDS_TASK_MANAGER_TAB_PREFIX
-    },
-    {
-        "/title2.html",
-        "Title Of Awesomeness",
-        Task::RENDERER,
-        IDS_TASK_MANAGER_TAB_PREFIX
-    },
-    {
-        "/title3.html",
-        "Title Of More Awesomeness",
-        Task::RENDERER,
-        IDS_TASK_MANAGER_TAB_PREFIX
-    },
-};
-
-const size_t kTestPagesLength = arraysize(kTestPages);
-
-}  // namespace
-
-// Defines a browser test class for testing the task manager tracking of tab
-// contents.
-class TabContentsTagTest : public InProcessBrowserTest {
- public:
-  TabContentsTagTest() {
-    EXPECT_TRUE(embedded_test_server()->InitializeAndWaitUntilReady());
-  }
-  ~TabContentsTagTest() override {}
-
-  void AddNewTestTabAt(int index, const char* test_page_file) {
-    int tabs_count_before = tabs_count();
-    GURL url = GetUrlOfFile(test_page_file);
-    AddTabAtIndex(index, url, ui::PAGE_TRANSITION_TYPED);
-    EXPECT_EQ(++tabs_count_before, tabs_count());
-  }
-
-  void NavigateToUrl(const char* test_page_file) {
-    ui_test_utils::NavigateToURL(browser(), GetUrlOfFile(test_page_file));
-  }
-
-  void CloseTabAt(int index) {
-    browser()->tab_strip_model()->CloseWebContentsAt(index,
-                                                     TabStripModel::CLOSE_NONE);
-  }
-
-  base::string16 GetTestPageExpectedTitle(const TestPageData& page_data) const {
-    // Pages with no title should fall back to their URL.
-    base::string16 title = base::UTF8ToUTF16(page_data.title);
-    if (title.empty()) {
-      GURL url = GetUrlOfFile(page_data.page_file);
-      title = base::UTF8ToUTF16(url.spec());
-    }
-    return l10n_util::GetStringFUTF16(page_data.expected_prefix_message, title);
-  }
-
-  base::string16 GetAboutBlankExpectedTitle() const {
-    return l10n_util::GetStringFUTF16(IDS_TASK_MANAGER_TAB_PREFIX,
-                                      base::UTF8ToUTF16("about:blank"));
-  }
-
-  int tabs_count() const { return browser()->tab_strip_model()->count(); }
-
-  const std::set<WebContentsTag*>& tracked_tags() const {
-    return WebContentsTagsManager::GetInstance()->tracked_tags();
-  }
-
- private:
-  GURL GetUrlOfFile(const char* test_page_file) const {
-    return embedded_test_server()->GetURL(test_page_file);
-  }
-
-  DISALLOW_COPY_AND_ASSIGN(TabContentsTagTest);
-};
-
-// Tests that TabContentsTags are being recorded correctly by the
-// WebContentsTagsManager.
-IN_PROC_BROWSER_TEST_F(TabContentsTagTest, BasicTagsTracking) {
-  // Browser tests start with a single tab.
-  EXPECT_EQ(1, tabs_count());
-  EXPECT_EQ(1U, tracked_tags().size());
-
-  // Add a bunch of tabs and make sure we're tracking them.
-  AddNewTestTabAt(0, kTestPages[0].page_file);
-  EXPECT_EQ(2, tabs_count());
-  EXPECT_EQ(2U, tracked_tags().size());
-
-  AddNewTestTabAt(1, kTestPages[1].page_file);
-  EXPECT_EQ(3, tabs_count());
-  EXPECT_EQ(3U, tracked_tags().size());
-
-  // Navigating the selected tab doesn't change the number of tabs nor the
-  // number of tags.
-  NavigateToUrl(kTestPages[2].page_file);
-  EXPECT_EQ(3, tabs_count());
-  EXPECT_EQ(3U, tracked_tags().size());
-
-  // Close a bunch of tabs and make sure we can notice that.
-  CloseTabAt(0);
-  CloseTabAt(0);
-  EXPECT_EQ(1, tabs_count());
-  EXPECT_EQ(1U, tracked_tags().size());
-}
-
-// Tests that the pre-task-manager-existing tabs are given to the task manager
-// once it starts observing.
-IN_PROC_BROWSER_TEST_F(TabContentsTagTest, PreExistingTaskProviding) {
-  // We start with the "about:blank" tab.
-  EXPECT_EQ(1, tabs_count());
-  EXPECT_EQ(1U, tracked_tags().size());
-
-  // Add a bunch of tabs and make sure when the task manager is created and
-  // starts observing sees those pre-existing tabs.
-  AddNewTestTabAt(0, kTestPages[0].page_file);
-  EXPECT_EQ(2, tabs_count());
-  EXPECT_EQ(2U, tracked_tags().size());
-  AddNewTestTabAt(1, kTestPages[1].page_file);
-  EXPECT_EQ(3, tabs_count());
-  EXPECT_EQ(3U, tracked_tags().size());
-
-  MockWebContentsTaskManager task_manager;
-  EXPECT_TRUE(task_manager.tasks().empty());
-  task_manager.StartObserving();
-  EXPECT_EQ(3U, task_manager.tasks().size());
-}
-
-// Tests that the task manager sees the correct tabs with their correct
-// corresponding tasks data.
-IN_PROC_BROWSER_TEST_F(TabContentsTagTest, PostExistingTaskProviding) {
-  // We start with the "about:blank" tab.
-  EXPECT_EQ(1, tabs_count());
-  EXPECT_EQ(1U, tracked_tags().size());
-
-  MockWebContentsTaskManager task_manager;
-  EXPECT_TRUE(task_manager.tasks().empty());
-  task_manager.StartObserving();
-  EXPECT_EQ(1U, task_manager.tasks().size());
-
-  const Task* first_tab_task = task_manager.tasks()[0];
-  EXPECT_EQ(Task::RENDERER, first_tab_task->GetType());
-  EXPECT_EQ(GetAboutBlankExpectedTitle(), first_tab_task->title());
-
-  // Add the test pages in order and test the provided tasks.
-  for (auto& test_page_data : kTestPages) {
-    AddNewTestTabAt(0, test_page_data.page_file);
-
-    const Task* task = task_manager.tasks().back();
-    EXPECT_EQ(test_page_data.task_type, task->GetType());
-    EXPECT_EQ(GetTestPageExpectedTitle(test_page_data), task->title());
-  }
-
-  EXPECT_EQ(1 + kTestPagesLength, task_manager.tasks().size());
-
-  // Close the last tab that was added. Make sure it doesn't show up in the
-  // task manager.
-  CloseTabAt(0);
-  EXPECT_EQ(kTestPagesLength, task_manager.tasks().size());
-  const base::string16 closed_tab_title =
-      GetTestPageExpectedTitle(kTestPages[kTestPagesLength - 1]);
-  for (auto& task : task_manager.tasks())
-    EXPECT_NE(closed_tab_title, task->title());
-}
-
-}  // namespace task_management
diff --git a/chrome/browser/task_management/providers/web_contents/tab_contents_task.cc b/chrome/browser/task_management/providers/web_contents/tab_contents_task.cc
deleted file mode 100644
index fdca98d..0000000
--- a/chrome/browser/task_management/providers/web_contents/tab_contents_task.cc
+++ /dev/null
@@ -1,75 +0,0 @@
-// Copyright 2015 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/task_management/providers/web_contents/tab_contents_task.h"
-
-#include "base/strings/utf_string_conversions.h"
-#include "chrome/browser/profiles/profile.h"
-#include "content/public/browser/web_contents.h"
-#include "extensions/browser/extension_registry.h"
-#include "extensions/browser/process_map.h"
-#include "extensions/common/constants.h"
-
-namespace task_management {
-
-namespace {
-
-bool HostsExtension(content::WebContents* web_contents) {
-  DCHECK(web_contents);
-  return web_contents->GetURL().SchemeIs(extensions::kExtensionScheme);
-}
-
-}  // namespace
-
-
-TabContentsTask::TabContentsTask(content::WebContents* web_contents)
-    : RendererTask(base::string16(),
-                   RendererTask::GetFaviconFromWebContents(web_contents),
-                   web_contents) {
-  set_title(GetCurrentTitle());
-}
-
-TabContentsTask::~TabContentsTask() {
-}
-
-void TabContentsTask::OnTitleChanged(content::NavigationEntry* entry) {
-  set_title(GetCurrentTitle());
-}
-
-void TabContentsTask::OnFaviconChanged() {
-  set_icon(*RendererTask::GetFaviconFromWebContents(web_contents()));
-}
-
-Task::Type TabContentsTask::GetType() const {
-  // A tab that loads an extension URL is considered to be an extension even
-  // though it's tracked as a TabContentsTask.
-  return HostsExtension(web_contents()) ? Task::EXTENSION : Task::RENDERER;
-}
-
-base::string16 TabContentsTask::GetCurrentTitle() const {
-  // Check if the URL is an app and if the tab is hoisting an extension.
-  Profile* profile =
-      Profile::FromBrowserContext(web_contents()->GetBrowserContext());
-  extensions::ProcessMap* process_map = extensions::ProcessMap::Get(profile);
-  extensions::ExtensionRegistry* extension_registry =
-      extensions::ExtensionRegistry::Get(profile);
-  GURL url = web_contents()->GetURL();
-  base::string16 url_spec = base::UTF8ToUTF16(url.spec());
-
-  bool is_app = process_map->Contains(process_id()) &&
-      extension_registry->enabled_extensions().GetAppByURL(url) != nullptr;
-  bool is_extension = HostsExtension(web_contents());
-  bool is_incognito = profile->IsOffTheRecord();
-
-  base::string16 tab_title =
-      RendererTask::GetTitleFromWebContents(web_contents());
-
-  // Fall back to the URL if the title is empty.
-  return PrefixRendererTitle(tab_title.empty() ? url_spec : tab_title,
-                             is_app,
-                             is_extension,
-                             is_incognito);
-}
-
-}  // namespace task_management
diff --git a/chrome/browser/task_management/providers/web_contents/tab_contents_task.h b/chrome/browser/task_management/providers/web_contents/tab_contents_task.h
deleted file mode 100644
index 2005967..0000000
--- a/chrome/browser/task_management/providers/web_contents/tab_contents_task.h
+++ /dev/null
@@ -1,32 +0,0 @@
-// Copyright 2015 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_TASK_MANAGEMENT_PROVIDERS_WEB_CONTENTS_TAB_CONTENTS_TASK_H_
-#define CHROME_BROWSER_TASK_MANAGEMENT_PROVIDERS_WEB_CONTENTS_TAB_CONTENTS_TASK_H_
-
-#include "chrome/browser/task_management/providers/web_contents/renderer_task.h"
-
-namespace task_management {
-
-// Defines a task manager representation of WebContents owned by the
-// TabStripModel.
-class TabContentsTask : public RendererTask {
- public:
-  explicit TabContentsTask(content::WebContents* web_contents);
-  ~TabContentsTask() override;
-
-  // task_management::RendererTask:
-  void OnTitleChanged(content::NavigationEntry* entry) override;
-  void OnFaviconChanged() override;
-  Type GetType() const override;
-
- private:
-  base::string16 GetCurrentTitle() const;
-
-  DISALLOW_COPY_AND_ASSIGN(TabContentsTask);
-};
-
-}  // namespace task_management
-
-#endif  // CHROME_BROWSER_TASK_MANAGEMENT_PROVIDERS_WEB_CONTENTS_TAB_CONTENTS_TASK_H_
diff --git a/chrome/browser/task_management/providers/web_contents/web_contents_task_provider.cc b/chrome/browser/task_management/providers/web_contents/web_contents_task_provider.cc
index fa93a16..4c24931 100644
--- a/chrome/browser/task_management/providers/web_contents/web_contents_task_provider.cc
+++ b/chrome/browser/task_management/providers/web_contents/web_contents_task_provider.cc
@@ -255,15 +255,11 @@ void WebContentsEntry::ClearTaskForFrame(RenderFrameHost* render_frame_host) {
 
 ////////////////////////////////////////////////////////////////////////////////
 
-WebContentsTaskProvider::WebContentsTaskProvider()
-    : entries_map_(),
-      is_updating_(false) {
+WebContentsTaskProvider::WebContentsTaskProvider() : entries_map_() {
 }
 
 WebContentsTaskProvider::~WebContentsTaskProvider() {
-  if (is_updating_) {
-    StopUpdating();
-  }
+  STLDeleteValues(&entries_map_);
 }
 
 void WebContentsTaskProvider::OnWebContentsTagCreated(
@@ -332,8 +328,6 @@ bool WebContentsTaskProvider::HasWebContents(
 }
 
 void WebContentsTaskProvider::StartUpdating() {
-  is_updating_ = true;
-
   // 1- Collect all pre-existing WebContents from the WebContentsTagsManager.
   WebContentsTagsManager* tags_manager = WebContentsTagsManager::GetInstance();
   for (auto& tag : tags_manager->tracked_tags())
@@ -344,8 +338,6 @@ void WebContentsTaskProvider::StartUpdating() {
 }
 
 void WebContentsTaskProvider::StopUpdating() {
-  is_updating_ = false;
-
   // 1- Stop observing.
   WebContentsTagsManager::GetInstance()->ClearProvider();
 
diff --git a/chrome/browser/task_management/providers/web_contents/web_contents_task_provider.h b/chrome/browser/task_management/providers/web_contents/web_contents_task_provider.h
index aeff7cc..cc9c7f3 100644
--- a/chrome/browser/task_management/providers/web_contents/web_contents_task_provider.h
+++ b/chrome/browser/task_management/providers/web_contents/web_contents_task_provider.h
@@ -58,10 +58,6 @@ class WebContentsTaskProvider : public TaskProvider {
   typedef std::map<content::WebContents*, WebContentsEntry*> EntryMap;
   EntryMap entries_map_;
 
-  // True if this provider is listening to WebContentsTags and updating its
-  // observers, false otherwise.
-  bool is_updating_;
-
   DISALLOW_COPY_AND_ASSIGN(WebContentsTaskProvider);
 };
 
diff --git a/chrome/browser/task_management/task_management_browsertest_util.cc b/chrome/browser/task_management/task_management_browsertest_util.cc
deleted file mode 100644
index a644a57..0000000
--- a/chrome/browser/task_management/task_management_browsertest_util.cc
+++ /dev/null
@@ -1,39 +0,0 @@
-// Copyright 2015 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/task_management/task_management_browsertest_util.h"
-
-#include "base/stl_util.h"
-
-namespace task_management {
-
-MockWebContentsTaskManager::MockWebContentsTaskManager()
-    : tasks_(),
-      provider_() {
-}
-
-MockWebContentsTaskManager::~MockWebContentsTaskManager() {
-}
-
-void MockWebContentsTaskManager::TaskAdded(Task* task) {
-  DCHECK(task);
-  DCHECK(!ContainsValue(tasks_, task));
-  tasks_.push_back(task);
-}
-
-void MockWebContentsTaskManager::TaskRemoved(Task* task) {
-  DCHECK(task);
-  DCHECK(ContainsValue(tasks_, task));
-  tasks_.erase(std::find(tasks_.begin(), tasks_.end(), task));
-}
-
-void MockWebContentsTaskManager::StartObserving() {
-  provider_.SetObserver(this);
-}
-
-void MockWebContentsTaskManager::StopObserving() {
-  provider_.ClearObserver();
-}
-
-}  // namespace task_management
diff --git a/chrome/browser/task_management/task_management_browsertest_util.h b/chrome/browser/task_management/task_management_browsertest_util.h
deleted file mode 100644
index 6ba4855..0000000
--- a/chrome/browser/task_management/task_management_browsertest_util.h
+++ /dev/null
@@ -1,40 +0,0 @@
-// Copyright 2015 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_TASK_MANAGEMENT_TASK_MANAGEMENT_BROWSERTEST_UTIL_H_
-#define CHROME_BROWSER_TASK_MANAGEMENT_TASK_MANAGEMENT_BROWSERTEST_UTIL_H_
-
-#include "chrome/browser/task_management/providers/task_provider_observer.h"
-#include "chrome/browser/task_management/providers/web_contents/web_contents_tags_manager.h"
-#include "chrome/browser/task_management/providers/web_contents/web_contents_task_provider.h"
-
-namespace task_management {
-
-// Defines a test class that will act as a task manager that is designed to
-// only observe the WebContents-based tasks.
-class MockWebContentsTaskManager : public TaskProviderObserver {
- public:
-  MockWebContentsTaskManager();
-  ~MockWebContentsTaskManager() override;
-
-  // task_management::TaskProviderObserver:
-  void TaskAdded(Task* task) override;
-  void TaskRemoved(Task* task) override;
-
-  // Start / Stop observing the WebContentsTaskProvider.
-  void StartObserving();
-  void StopObserving();
-
-  const std::vector<Task*>& tasks() const { return tasks_; }
-
- private:
-  std::vector<Task*> tasks_;
-  WebContentsTaskProvider provider_;
-
-  DISALLOW_COPY_AND_ASSIGN(MockWebContentsTaskManager);
-};
-
-}  // namespace task_management
-
-#endif  // CHROME_BROWSER_TASK_MANAGEMENT_TASK_MANAGEMENT_BROWSERTEST_UTIL_H_
diff --git a/chrome/browser/task_management/web_contents_tags.cc b/chrome/browser/task_management/web_contents_tags.cc
index 1e5a720..9371a0d 100644
--- a/chrome/browser/task_management/web_contents_tags.cc
+++ b/chrome/browser/task_management/web_contents_tags.cc
@@ -7,7 +7,6 @@
 #include "chrome/browser/task_management/providers/web_contents/background_contents_tag.h"
 #include "chrome/browser/task_management/providers/web_contents/devtools_tag.h"
 #include "chrome/browser/task_management/providers/web_contents/prerender_tag.h"
-#include "chrome/browser/task_management/providers/web_contents/tab_contents_tag.h"
 #include "chrome/browser/task_management/providers/web_contents/web_contents_tags_manager.h"
 #include "content/public/browser/web_contents.h"
 
@@ -71,17 +70,6 @@ void WebContentsTags::CreateForPrerenderContents(
 }
 
 // static
-void WebContentsTags::CreateForTabContents(content::WebContents* web_contents) {
-#if defined(ENABLE_TASK_MANAGER)
-  if (!WebContentsTag::FromWebContents(web_contents)) {
-    TagWebContents(web_contents,
-                   new TabContentsTag(web_contents),
-                   WebContentsTag::kTagKey);
-  }
-#endif  // defined(ENABLE_TASK_MANAGER)
-}
-
-// static
 void WebContentsTags::ClearTag(content::WebContents* web_contents) {
 #if defined(ENABLE_TASK_MANAGER)
   const WebContentsTag* tag = WebContentsTag::FromWebContents(web_contents);
diff --git a/chrome/browser/task_management/web_contents_tags.h b/chrome/browser/task_management/web_contents_tags.h
index c2794f6..3c92939 100644
--- a/chrome/browser/task_management/web_contents_tags.h
+++ b/chrome/browser/task_management/web_contents_tags.h
@@ -46,13 +46,6 @@ class WebContentsTags {
   // owned by |web_contents|.
   static void CreateForPrerenderContents(content::WebContents* web_contents);
 
-  // Tag a WebContents owned by the TabStripModel so that it shows up in the
-  // task manager. Calling this function creates a TabContentsTag, and attaches
-  // it to |web_contents|. If an instance is already attached, this does
-  // nothing. The resulting tag does not have to be cleaned up by the caller, as
-  // it is owned by |web_contents|.
-  static void CreateForTabContents(content::WebContents* web_contents);
-
   // Clears the task-manager tag, created by any of the above functions, from
   // the given |web_contents| if any.
   // Clearing the tag is necessary only when you need to re-tag an existing
diff --git a/chrome/browser/ui/browser.cc b/chrome/browser/ui/browser.cc
index 242f79b..8805274 100644
--- a/chrome/browser/ui/browser.cc
+++ b/chrome/browser/ui/browser.cc
@@ -84,7 +84,6 @@
 #include "chrome/browser/sync/sync_ui_util.h"
 #include "chrome/browser/tab_contents/retargeting_details.h"
 #include "chrome/browser/tab_contents/tab_util.h"
-#include "chrome/browser/task_management/web_contents_tags.h"
 #include "chrome/browser/themes/theme_service.h"
 #include "chrome/browser/themes/theme_service_factory.h"
 #include "chrome/browser/translate/chrome_translate_client.h"
@@ -1692,9 +1691,6 @@ void Browser::WebContentsCreated(WebContents* source_contents,
   // AddNewContents.
   TabHelpers::AttachTabHelpers(new_contents);
 
-  // Make the tab show up in the task manager.
-  task_management::WebContentsTags::CreateForTabContents(new_contents);
-
   // Notify.
   RetargetingDetails details;
   details.source_web_contents = source_contents;
diff --git a/chrome/browser/ui/browser_navigator.cc b/chrome/browser/ui/browser_navigator.cc
index fbd9415..7be37f7 100644
--- a/chrome/browser/ui/browser_navigator.cc
+++ b/chrome/browser/ui/browser_navigator.cc
@@ -17,7 +17,6 @@
 #include "chrome/browser/prerender/prerender_manager_factory.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/tab_contents/tab_util.h"
-#include "chrome/browser/task_management/web_contents_tags.h"
 #include "chrome/browser/ui/browser.h"
 #include "chrome/browser/ui/browser_finder.h"
 #include "chrome/browser/ui/browser_instant_controller.h"
@@ -60,9 +59,6 @@ class BrowserNavigatorWebContentsAdoption {
  public:
   static void AttachTabHelpers(content::WebContents* contents) {
     TabHelpers::AttachTabHelpers(contents);
-
-    // Make the tab show up in the task manager.
-    task_management::WebContentsTags::CreateForTabContents(contents);
   }
 };
 
diff --git a/chrome/browser/ui/browser_tab_strip_model_delegate.cc b/chrome/browser/ui/browser_tab_strip_model_delegate.cc
index dcf1492..3fcd438 100644
--- a/chrome/browser/ui/browser_tab_strip_model_delegate.cc
+++ b/chrome/browser/ui/browser_tab_strip_model_delegate.cc
@@ -10,7 +10,6 @@
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/sessions/tab_restore_service.h"
 #include "chrome/browser/sessions/tab_restore_service_factory.h"
-#include "chrome/browser/task_management/web_contents_tags.h"
 #include "chrome/browser/ui/browser.h"
 #include "chrome/browser/ui/browser_commands.h"
 #include "chrome/browser/ui/browser_navigator.h"
@@ -86,9 +85,6 @@ Browser* BrowserTabStripModelDelegate::CreateNewStripWithContents(
 void BrowserTabStripModelDelegate::WillAddWebContents(
     content::WebContents* contents) {
   TabHelpers::AttachTabHelpers(contents);
-
-  // Make the tab show up in the task manager.
-  task_management::WebContentsTags::CreateForTabContents(contents);
 }
 
 int BrowserTabStripModelDelegate::GetDragActions() const {
diff --git a/chrome/chrome_browser.gypi b/chrome/chrome_browser.gypi
index 335fcdc..6b0f084 100644
--- a/chrome/chrome_browser.gypi
+++ b/chrome/chrome_browser.gypi
@@ -3017,10 +3017,6 @@
       'browser/task_management/providers/web_contents/renderer_task.h',
       'browser/task_management/providers/web_contents/subframe_task.cc',
       'browser/task_management/providers/web_contents/subframe_task.h',
-      'browser/task_management/providers/web_contents/tab_contents_tag.cc',
-      'browser/task_management/providers/web_contents/tab_contents_tag.h',
-      'browser/task_management/providers/web_contents/tab_contents_task.cc',
-      'browser/task_management/providers/web_contents/tab_contents_task.h',
       'browser/task_management/providers/web_contents/web_contents_tag.cc',
       'browser/task_management/providers/web_contents/web_contents_tag.h',
       'browser/task_management/providers/web_contents/web_contents_tags_manager.cc',
diff --git a/chrome/chrome_tests.gypi b/chrome/chrome_tests.gypi
index 142639a..f5c869f 100644
--- a/chrome/chrome_tests.gypi
+++ b/chrome/chrome_tests.gypi
@@ -406,9 +406,6 @@
       'browser/tab_contents/view_source_browsertest.cc',
       'browser/task_management/providers/web_contents/background_contents_tag_browsertest.cc',
       'browser/task_management/providers/web_contents/devtools_tag_browsertest.cc',
-      'browser/task_management/providers/web_contents/tab_contents_tag_browsertest.cc',
-      'browser/task_management/task_management_browsertest_util.cc',
-      'browser/task_management/task_management_browsertest_util.h',
       'browser/task_manager/task_manager_browsertest.cc',
       'browser/task_manager/task_manager_browsertest_util.cc',
       'browser/task_manager/task_manager_browsertest_util.h',