Include tab IDs when reporting data use accounting.

chrome/browser/data_usage/tab_id_provider.cc

+// Copyright (c) 2015 The Chromium Authors. All rights reserved.

[bengr, 2015/11/05 00:00:38]

"(c)" -> ""

[sclittle, 2015/11/05 01:22:48]

Done.

+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "chrome/browser/data_usage/tab_id_provider.h"
+
+#include <vector>
+
+#include "base/bind.h"
+#include "base/callback.h"
+#include "base/location.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/single_thread_task_runner.h"
+#include "base/task_runner.h"
+#include "base/task_runner_util.h"
+
+namespace chrome_browser_data_usage {
+
+namespace {
+
+// Convenience typedefs for clarity.
+typedef base::Callback<int32_t(void)> TabIdGetter;
+typedef base::Callback<void(int32_t)> TabIdCallback;
+
+}  // namespace
+
+// Object that can run a list of callbacks that take tab IDs. New callbacks
+// can be added before it starts running the callbacks. Callbacks added will

[bengr, 2015/11/05 00:00:38]

can -> can only?
will -> will each

[sclittle, 2015/11/05 01:22:48]

Done.

+// be run exactly once.
+class TabIdProvider::CallbackRunner {
+ public:
+  CallbackRunner() : is_done_(false), weak_ptr_factory_(this) {}
+
+  ~CallbackRunner() {
+    // Ensure that no callbacks are abandoned without being run.
+    if (!is_done_)
+      RunAll(-1);
+  }
+
+  // Adds a new callback to be run later. New callbacks must not be added after
+  // RunAll has been called.
+  void AddCallback(const TabIdCallback& callback) {
+    DCHECK(thread_checker_.CalledOnValidThread());
+    DCHECK(!is_done_);
+    callbacks_.push_back(callback);
+  }
+
+  // Runs all the callbacks in the order that they were added. This method must
+  // not be called more than once.
+  void RunAll(int32_t tab_id) {
+    DCHECK(thread_checker_.CalledOnValidThread());
+    DCHECK(!is_done_);
+    is_done_ = true;
+    // It's safe to run the |callbacks_| while iterating through them because
+    // |callbacks_| can no longer be modified at this point, so it's impossible
+    // for one of the |callbacks_| to add more callbacks to this CallbackRunner.
+    for (const auto& callback : callbacks_)
+      callback.Run(tab_id);
+    callbacks_.clear();
+  }
+
+  base::WeakPtr<CallbackRunner> GetWeakPtr() {
+    DCHECK(thread_checker_.CalledOnValidThread());
+    return weak_ptr_factory_.GetWeakPtr();
+  }
+
+ private:
+  base::ThreadChecker thread_checker_;
+  bool is_done_;
+  std::vector<TabIdCallback> callbacks_;
+  base::WeakPtrFactory<CallbackRunner> weak_ptr_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(CallbackRunner);
+};
+
+TabIdProvider::TabIdProvider(base::TaskRunner* task_runner,
+                             const tracked_objects::Location& from_here,
+                             const TabIdGetter& tab_id_getter)
+    : is_tab_id_ready_(false), tab_id_(-1), weak_ptr_factory_(this) {
+  scoped_ptr<CallbackRunner> callback_runner(new CallbackRunner());
+  weak_callback_runner_ = callback_runner->GetWeakPtr();
+  callback_runner->AddCallback(
+      base::Bind(&TabIdProvider::OnTabIdReady, GetWeakPtr()));
+
+  // The posted task takes ownership of |callback_runner|. If the task fails to
+  // be posted, then the destructor of |callback_runner| will pass a tab ID of
+  // -1 to OnTabIdReady, so that case doesn't need to be explicitly handled
+  // here.
+  base::PostTaskAndReplyWithResult(
+      task_runner, from_here, tab_id_getter,
+      base::Bind(&CallbackRunner::RunAll,
+                 base::Owned(callback_runner.release())));
+}
+
+TabIdProvider::~TabIdProvider() {}
+
+void TabIdProvider::ProvideTabId(const TabIdCallback& callback) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  if (is_tab_id_ready_) {
+    callback.Run(tab_id_);
+    return;
+  }
+  if (weak_callback_runner_) {
+    weak_callback_runner_->AddCallback(callback);
+    return;
+  }
+  // If no cached tab ID is available and |weak_callback_runner_| has been
+  // destroyed, pass a tab ID of -1 to the callback indicating that no tab was
+  // found.
+  callback.Run(-1);
+}
+
+base::WeakPtr<TabIdProvider> TabIdProvider::GetWeakPtr() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  return weak_ptr_factory_.GetWeakPtr();
+}
+
+// static
+const void* TabIdProvider::kUserDataKey =
+    static_cast<void*>(&TabIdProvider::kUserDataKey);
+
+void TabIdProvider::OnTabIdReady(int32_t tab_id) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(!is_tab_id_ready_);
+  tab_id_ = tab_id;
+  is_tab_id_ready_ = true;
+}
+
+}  // namespace chrome_browser_data_usage