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// Copyright (c) 2012 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 "content/browser/field_trial_synchronizer.h"
#include "base/bind.h"
#include "base/check_op.h"
#include "base/task/post_task.h"
#include "base/threading/thread.h"
#include "components/metrics/persistent_system_profile.h"
#include "components/variations/variations_client.h"
#include "content/common/renderer_variations_configuration.mojom.h"
#include "content/public/browser/browser_context.h"
#include "content/public/browser/browser_task_traits.h"
#include "content/public/browser/browser_thread.h"
#include "content/public/browser/render_process_host.h"
#include "mojo/public/cpp/bindings/associated_remote.h"
namespace content {
namespace {
void AddFieldTrialToPersistentSystemProfile(const std::string& field_trial_name,
const std::string& group_name) {
// Note this in the persistent profile as it will take a while for a new
// "complete" profile to be generated.
metrics::GlobalPersistentSystemProfile::GetInstance()->AddFieldTrial(
field_trial_name, group_name);
}
} // namespace
FieldTrialSynchronizer::FieldTrialSynchronizer() {
bool success = base::FieldTrialList::AddObserver(this);
// Ensure the observer was actually registered.
DCHECK(success);
variations::VariationsIdsProvider::GetInstance()->AddObserver(this);
NotifyAllRenderersOfVariationsHeader();
}
void FieldTrialSynchronizer::NotifyAllRenderersOfFieldTrial(
const std::string& field_trial_name,
const std::string& group_name) {
// To iterate over RenderProcessHosts, or to send messages to the hosts, we
// need to be on the UI thread.
DCHECK_CURRENTLY_ON(BrowserThread::UI);
AddFieldTrialToPersistentSystemProfile(field_trial_name, group_name);
for (RenderProcessHost::iterator it(RenderProcessHost::AllHostsIterator());
!it.IsAtEnd(); it.Advance()) {
auto* host = it.GetCurrentValue();
IPC::ChannelProxy* channel = host->GetChannel();
// channel might be null in tests.
if (host->IsInitializedAndNotDead() && channel) {
mojo::AssociatedRemote<mojom::RendererVariationsConfiguration>
renderer_variations_configuration;
channel->GetRemoteAssociatedInterface(&renderer_variations_configuration);
renderer_variations_configuration->SetFieldTrialGroup(field_trial_name,
group_name);
}
}
}
void FieldTrialSynchronizer::OnFieldTrialGroupFinalized(
const std::string& field_trial_name,
const std::string& group_name) {
// The FieldTrialSynchronizer may have been created before any BrowserThread
// is created, so we don't need to synchronize with child processes in which
// case there are no child processes to notify yet. But we want to update the
// persistent system profile, thus the histogram data recorded in the reduced
// mode will be tagged to its corresponding field trial experiment.
if (!BrowserThread::IsThreadInitialized(BrowserThread::UI)) {
AddFieldTrialToPersistentSystemProfile(field_trial_name, group_name);
return;
}
RunOrPostTaskOnThread(
FROM_HERE, BrowserThread::UI,
base::BindOnce(&FieldTrialSynchronizer::NotifyAllRenderersOfFieldTrial,
this, field_trial_name, group_name));
}
// static
void FieldTrialSynchronizer::NotifyAllRenderersOfVariationsHeader() {
// To iterate over RenderProcessHosts, or to send messages to the hosts, we
// need to be on the UI thread.
DCHECK_CURRENTLY_ON(BrowserThread::UI);
for (RenderProcessHost::iterator it(RenderProcessHost::AllHostsIterator());
!it.IsAtEnd(); it.Advance()) {
UpdateRendererVariationsHeader(it.GetCurrentValue());
}
}
// static
void FieldTrialSynchronizer::UpdateRendererVariationsHeader(
RenderProcessHost* host) {
if (!host->IsInitializedAndNotDead())
return;
IPC::ChannelProxy* channel = host->GetChannel();
// |channel| might be null in tests.
if (!channel)
return;
variations::VariationsClient* client =
host->GetBrowserContext()->GetVariationsClient();
// |client| might be null in tests.
if (!client || client->IsOffTheRecord())
return;
mojo::AssociatedRemote<mojom::RendererVariationsConfiguration>
renderer_variations_configuration;
channel->GetRemoteAssociatedInterface(&renderer_variations_configuration);
renderer_variations_configuration->SetVariationsHeaders(
client->GetVariationsHeaders());
}
void FieldTrialSynchronizer::VariationIdsHeaderUpdated() {
// PostTask to avoid recursive lock.
base::PostTask(
FROM_HERE, BrowserThread::UI,
base::BindOnce(
&FieldTrialSynchronizer::NotifyAllRenderersOfVariationsHeader));
}
FieldTrialSynchronizer::~FieldTrialSynchronizer() {
base::FieldTrialList::RemoveObserver(this);
variations::VariationsIdsProvider::GetInstance()->RemoveObserver(this);
}
} // namespace content
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