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"
+
+namespace media_router {
+
+IssueManager::IssueManager() : top_issue_(nullptr) {
+}
+
+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());
+  for (auto issue_iter = issues_.begin(); issue_iter != issues_.end();
+       ++issue_iter) {
+    if (issue_iter->id() == issue_id) {
+      if (top_issue_ && top_issue_->id() == issue_id) {
+        // Invalidate the top issue ptr if we are clearing it now.
+        top_issue_ = nullptr;
+      }
+      issues_.erase(issue_iter);
+      MaybeUpdateTopIssue();
+      return;
+    }
+  }
+}
+
+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() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  auto it = issues_.begin();
+  while (it != issues_.end()) {
+    if (it->is_global()) {
+      if (top_issue_ && it->Equals(*top_issue_)) {
+        top_issue_ = nullptr;

[apacible, 2015/05/01 20:18:08]

Do we need a comment about invalidating top_issue_ similar to L32 here? Same
with L75.

[Kevin Marshall, 2015/05/01 20:26:03]

Done.

+      }
+      issues_.erase(it++);
+    } else {
+      ++it;
+    }
+  }
+  MaybeUpdateTopIssue();
+}
+
+void IssueManager::ClearIssuesWithRouteId(const MediaRouteId& route_id) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  auto it = issues_.begin();
+  while (it != issues_.end()) {
+    if (it->route_id() == route_id) {
+      if (top_issue_ && it->Equals(*top_issue_)) {
+        top_issue_ = nullptr;
+      }
+      issues_.erase(it++);
+    } else {
+      ++it;
+    }
+  }
+  MaybeUpdateTopIssue();
+}
+
+void IssueManager::RegisterObserver(IssuesObserver* observer) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(observer);
+  DCHECK(!issues_observers_.HasObserver(observer));
+
+  issues_observers_.AddObserver(observer);
+  if (top_issue_)
+    observer->OnIssueUpdated(top_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 (!top_issue_ || !new_top_issue->Equals(*top_issue_)) {
+    top_issue_ = new_top_issue;
+    FOR_EACH_OBSERVER(IssuesObserver, issues_observers_,
+                      OnIssueUpdated(top_issue_));
+  }
+}
+
+}  // namespace media_router