Upstream the Media Router's Issue class.

chrome/browser/media/router/issue_manager.cc

+// 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/media/router/issue_manager.h"
+
+#include <algorithm>
+
+namespace media_router {
+
+IssueManager::IssueManager() {
+}
+
+IssueManager::~IssueManager() {
+}
+
+void IssueManager::AddIssue(const Issue& issue) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  for (const Issue& next_issue : issues_) {
+    if (next_issue.Equals(issue)) {
+      return;
+    }
+  }
+  issues_.push_back(issue);
+  MaybeUpdateTopIssue();
+}
+
+void IssueManager::ClearIssue(const Issue::IssueId& issue_id) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  issues_.erase(std::remove_if(issues_.begin(), issues_.end(),
+                               [&issue_id](const Issue& issue) {
+                                 return issue_id == issue.id();
+                               }),
+                issues_.end());
+  MaybeUpdateTopIssue();
+}
+
+size_t IssueManager::GetIssueCount() const {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  return issues_.size();
+}
+
+void IssueManager::ClearAllIssues() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  issues_.clear();
+  MaybeUpdateTopIssue();
+}
+
+void IssueManager::ClearGlobalIssues() {

[DaleCurtis, 2015/05/04 23:48:30]

Have you tried calling this when there are no global issues? I forget if
remove_if protects you against erasing() and empty iterator.

+  DCHECK(thread_checker_.CalledOnValidThread());
+  issues_.erase(
+      std::remove_if(issues_.begin(), issues_.end(), [](const Issue& issue) {
+        return issue.is_global();
+      }), issues_.end());
+  MaybeUpdateTopIssue();
+}
+
+void IssueManager::ClearIssuesWithRouteId(const MediaRouteId& route_id) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  issues_.erase(std::remove_if(issues_.begin(), issues_.end(),
+                               [route_id](const Issue& issue) {

[DaleCurtis, 2015/05/04 23:48:30]

&route_id ?

+                                 return route_id == issue.route_id();
+                               }),
+                issues_.end());
+  MaybeUpdateTopIssue();
+}
+
+void IssueManager::RegisterObserver(IssuesObserver* observer) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(observer);
+  DCHECK(!issues_observers_.HasObserver(observer));
+
+  issues_observers_.AddObserver(observer);
+  if (!top_issue_id_.empty()) {
+    // Find the current top issue and report it to the observer.
+    for (const auto& next_issue : issues_) {
+      if (next_issue.id() == top_issue_id_) {
+        observer->OnIssueUpdated(&next_issue);
+      }
+    }
+  }
+}
+
+void IssueManager::UnregisterObserver(IssuesObserver* observer) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  issues_observers_.RemoveObserver(observer);
+}
+
+void IssueManager::MaybeUpdateTopIssue() {
+  if (issues_.empty()) {
+    return;
+  }
+
+  // Select the first blocking issue in the list of issues.
+  // If there are none, simply select the first issue in the list.
+  Issue* new_top_issue = &(issues_.front());
+  for (auto it = issues_.begin(); it != issues_.end(); ++it) {
+    // The first blocking issue is of higher priority than the first issue.
+    if (it->is_blocking()) {
+      new_top_issue = &(*it);
+      break;
+    }
+  }
+
+  // If we've found a new top issue, then report it via the observer.
+  if (new_top_issue->id() != top_issue_id_) {
+    top_issue_id_ = new_top_issue->id();
+    FOR_EACH_OBSERVER(IssuesObserver, issues_observers_,
+                      OnIssueUpdated(new_top_issue));
+  }
+}
+
+}  // namespace media_router