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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 "chrome/renderer/prerender/prerender_helper.h"
#include "base/metrics/field_trial.h"
#include "base/metrics/histogram_macros.h"
#include "chrome/common/prerender_url_loader_throttle.h"
#include "components/prerender/common/prerender_messages.h"
#include "content/public/renderer/document_state.h"
#include "content/public/renderer/render_frame.h"
#include "content/public/renderer/render_thread.h"
#include "content/public/renderer/render_view.h"
#include "third_party/blink/public/common/browser_interface_broker_proxy.h"
#include "third_party/blink/public/web/web_frame.h"
#include "third_party/blink/public/web/web_view.h"
namespace prerender {
PrerenderHelper::PrerenderHelper(content::RenderFrame* render_frame,
prerender::mojom::PrerenderMode prerender_mode,
const std::string& histogram_prefix)
: content::RenderFrameObserver(render_frame),
content::RenderFrameObserverTracker<PrerenderHelper>(render_frame),
prerender_mode_(prerender_mode),
histogram_prefix_(histogram_prefix),
start_time_(base::TimeTicks::Now()) {
DCHECK_NE(prerender_mode_, prerender::mojom::PrerenderMode::kNoPrerender);
}
PrerenderHelper::~PrerenderHelper() = default;
// static
std::unique_ptr<blink::URLLoaderThrottle> PrerenderHelper::MaybeCreateThrottle(
int render_frame_id) {
content::RenderFrame* render_frame =
content::RenderFrame::FromRoutingID(render_frame_id);
auto* prerender_helper =
render_frame ? PrerenderHelper::Get(
render_frame->GetRenderView()->GetMainRenderFrame())
: nullptr;
if (!prerender_helper)
return nullptr;
mojo::PendingRemote<prerender::mojom::PrerenderCanceler> canceler;
render_frame->GetBrowserInterfaceBroker()->GetInterface(
canceler.InitWithNewPipeAndPassReceiver());
auto throttle = std::make_unique<PrerenderURLLoaderThrottle>(
prerender_helper->prerender_mode(), prerender_helper->histogram_prefix(),
std::move(canceler));
prerender_helper->AddThrottle(throttle->AsWeakPtr());
return throttle;
}
// static.
bool PrerenderHelper::IsPrerendering(const content::RenderFrame* render_frame) {
return PrerenderHelper::GetPrerenderMode(render_frame) !=
prerender::mojom::PrerenderMode::kNoPrerender;
}
// static.
prerender::mojom::PrerenderMode PrerenderHelper::GetPrerenderMode(
const content::RenderFrame* render_frame) {
PrerenderHelper* helper = PrerenderHelper::Get(render_frame);
if (!helper)
return prerender::mojom::PrerenderMode::kNoPrerender;
DCHECK_NE(helper->prerender_mode_,
prerender::mojom::PrerenderMode::kNoPrerender);
return helper->prerender_mode_;
}
void PrerenderHelper::DidFinishDocumentLoad() {
if (prerender_mode_ != prerender::mojom::PrerenderMode::kPrefetchOnly)
return;
parsed_time_ = base::TimeTicks::Now();
prefetch_finished_ = true;
if (prefetch_count_ == 0)
SendPrefetchFinished();
}
bool PrerenderHelper::OnMessageReceived(
const IPC::Message& message) {
IPC_BEGIN_MESSAGE_MAP(PrerenderHelper, message)
IPC_MESSAGE_HANDLER(PrerenderMsg_SetIsPrerendering, OnSetIsPrerendering)
IPC_END_MESSAGE_MAP()
// Return false on PrerenderMsg_SetIsPrerendering so other observers can see
// the message.
return false;
}
void PrerenderHelper::OnDestruct() {
delete this;
}
void PrerenderHelper::OnSetIsPrerendering(prerender::mojom::PrerenderMode mode,
const std::string& histogram_prefix) {
// Immediately after construction, |this| may receive the message that
// triggered its creation. If so, ignore it.
if (mode != prerender::mojom::PrerenderMode::kNoPrerender)
return;
std::vector<base::WeakPtr<PrerenderURLLoaderThrottle>> throttles =
std::move(throttles_);
// |this| must be deleted so PrerenderHelper::IsPrerendering returns false
// when the visibility state is updated, so the visibility state string will
// not be "prerendered".
delete this;
for (auto& throttle : throttles) {
if (throttle)
throttle->PrerenderUsed();
}
}
void PrerenderHelper::AddThrottle(
const base::WeakPtr<PrerenderURLLoaderThrottle>& throttle) {
// Keep track of how many pending throttles we have, as we want to defer
// sending the "prefetch finished" signal until they are destroyed. This is
// important since that signal tells the browser that it can tear down this
// renderer which could interrupt subresource prefetching.
if (prerender_mode_ == prerender::mojom::PrerenderMode::kPrefetchOnly) {
prefetch_count_++;
throttle->set_destruction_closure(base::BindOnce(
&PrerenderHelper::OnThrottleDestroyed, weak_factory_.GetWeakPtr()));
}
throttles_.push_back(throttle);
}
void PrerenderHelper::OnThrottleDestroyed() {
if (--prefetch_count_ == 0 && prefetch_finished_) {
UMA_HISTOGRAM_MEDIUM_TIMES(
"Prerender.NoStatePrefetchRendererLifetimeExtension",
base::TimeTicks::Now() - parsed_time_);
SendPrefetchFinished();
}
}
void PrerenderHelper::SendPrefetchFinished() {
DCHECK(prefetch_count_ == 0 && prefetch_finished_);
UMA_HISTOGRAM_MEDIUM_TIMES("Prerender.NoStatePrefetchRendererParseTime",
parsed_time_ - start_time_);
// TODO(darin): Perhaps this should be a routed message (frame level).
content::RenderThread::Get()->Send(new PrerenderHostMsg_PrefetchFinished());
}
} // namespace prerender
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