Lingqi Chi (Gerrit)

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Jun 17, 2026, 5:40:31 AM (12 days ago) Jun 17

to Hiroki Nakagawa, Taiyo Mizuhashi, Chromium LUCI CQ, chromium...@chromium.org, prerendering-reviews, gavin...@chromium.org, tburkar...@chromium.org

Attention needed from Hiroki Nakagawa and Taiyo Mizuhashi

Lingqi Chi voted and added 1 comment

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File-level comment, Patchset 5 (Latest):

Lingqi Chi . resolved

PTAL 😊

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Hiroki Nakagawa (Gerrit)

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Jun 18, 2026, 1:04:07 AM (12 days ago) Jun 18

to Lingqi Chi, Taiyo Mizuhashi, Chromium LUCI CQ, chromium...@chromium.org, prerendering-reviews, gavin...@chromium.org, tburkar...@chromium.org

Attention needed from Lingqi Chi and Taiyo Mizuhashi

Hiroki Nakagawa voted and added 5 comments

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+1

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File-level comment, Patchset 5 (Latest):

Hiroki Nakagawa . resolved

LGTM, thanks!

File content/browser/preloading/prerender/prerender_browsertest.cc

Line 19037, Patchset 5 (Latest): SameSitePrerenderReusesProcess) {

Hiroki Nakagawa . unresolved

Actually this test confirms the `same-origin` case. Can we also confirm the same-site cross-origin case?

Line 19087, Patchset 5 (Latest): // Use PrerenderHostRegistry to cancel.

Hiroki Nakagawa . unresolved

This comment may not be useful?

File content/browser/preloading/prerender/prerender_host.cc

Line 518, Patchset 5 (Latest): scoped_refptr<SiteInstanceImpl> site_instance;

Hiroki Nakagawa . unresolved

Do we need to split initialization from declaration? Can we keep the original structure?

```
    scoped_refptr<SiteInstanceImpl> site_instance =
        base::FeatureList::IsEnabled(kCreatePrerenderSiteInstanceWithURL)
            ? SiteInstanceImpl::CreateForURL(web_contents.GetBrowserContext(),
                                             attributes.prerendering_url)
            : SiteInstanceImpl::Create(web_contents.GetBrowserContext());
```

Line 519, Patchset 5 (Latest):


    // TODO(https://crbug.com/524800804): Add the following restrictions:
    // 1. Limit to prerender-until-script for now.
    // 2. For moderate eagerness only
    // 3. Disallow Target_hint = 'blank' to use the same process.
    // 4. Disallow cross-site prerendering to reuse the process.

Hiroki Nakagawa . unresolved

These comments should be placed on the following if-condition, not on the initialization of `site_instance`?

```
    // TODO(https://crbug.com/524800804): Add the following restrictions:
    // 1. Limit to prerender-until-script for now.
    // 2. For moderate eagerness only
    // 3. Disallow Target_hint = 'blank' to use the same process.
    // 4. Disallow cross-site prerendering to reuse the process.
    if (!attributes.IsBrowserInitiated() &&
        attributes.initiator_frame_token.has_value() &&
        base::FeatureList::IsEnabled(
            features::kPrerender2ReuseInitiatorProcess)) {
      RenderFrameHostImpl* initiator_rfh = RenderFrameHostImpl::FromFrameToken(
          attributes.initiator_process_id,
          attributes.initiator_frame_token.value());
      if (initiator_rfh) {
        site_instance->ReuseExistingProcessIfPossible(
            initiator_rfh->GetProcess());
      }
    }
```

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Lingqi Chi (Gerrit)

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Jun 18, 2026, 1:16:16 AM (12 days ago) Jun 18

to Hiroki Nakagawa, Taiyo Mizuhashi, Chromium LUCI CQ, chromium...@chromium.org, prerendering-reviews, gavin...@chromium.org, tburkar...@chromium.org

Attention needed from Taiyo Mizuhashi

Lingqi Chi voted and added 5 comments

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+1

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File-level comment, Patchset 5:

Lingqi Chi . resolved

thanks!

File content/browser/preloading/prerender/prerender_browsertest.cc

Line 19037, Patchset 5: SameSitePrerenderReusesProcess) {

Hiroki Nakagawa . resolved

Actually this test confirms the `same-origin` case. Can we also confirm the same-site cross-origin case?

Lingqi Chi

oh indeed.. thinking of that, let me start with same-origin prerendering to minimize the security concern.

Line 19087, Patchset 5: // Use PrerenderHostRegistry to cancel.

Hiroki Nakagawa . resolved

This comment may not be useful?

Lingqi Chi

Done

File content/browser/preloading/prerender/prerender_host.cc

Line 518, Patchset 5: scoped_refptr<SiteInstanceImpl> site_instance;

Hiroki Nakagawa . resolved

Do we need to split initialization from declaration? Can we keep the original structure?

```
    scoped_refptr<SiteInstanceImpl> site_instance =
        base::FeatureList::IsEnabled(kCreatePrerenderSiteInstanceWithURL)
            ? SiteInstanceImpl::CreateForURL(web_contents.GetBrowserContext(),
                                             attributes.prerendering_url)
            : SiteInstanceImpl::Create(web_contents.GetBrowserContext());
```

Lingqi Chi

Done.

Line 519, Patchset 5:


    // TODO(https://crbug.com/524800804): Add the following restrictions:
    // 1. Limit to prerender-until-script for now.
    // 2. For moderate eagerness only
    // 3. Disallow Target_hint = 'blank' to use the same process.
    // 4. Disallow cross-site prerendering to reuse the process.

Hiroki Nakagawa . resolved

These comments should be placed on the following if-condition, not on the initialization of `site_instance`?

```
    // TODO(https://crbug.com/524800804): Add the following restrictions:
    // 1. Limit to prerender-until-script for now.
    // 2. For moderate eagerness only
    // 3. Disallow Target_hint = 'blank' to use the same process.
    // 4. Disallow cross-site prerendering to reuse the process.
    if (!attributes.IsBrowserInitiated() &&
        attributes.initiator_frame_token.has_value() &&
        base::FeatureList::IsEnabled(
            features::kPrerender2ReuseInitiatorProcess)) {
      RenderFrameHostImpl* initiator_rfh = RenderFrameHostImpl::FromFrameToken(
          attributes.initiator_process_id,
          attributes.initiator_frame_token.value());
      if (initiator_rfh) {
        site_instance->ReuseExistingProcessIfPossible(
            initiator_rfh->GetProcess());
      }
    }
```

Lingqi Chi

Done

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Lingqi Chi (Gerrit)

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Jun 18, 2026, 9:39:03 PM (11 days ago) Jun 18

to Hiroki Nakagawa, Taiyo Mizuhashi, Chromium LUCI CQ, chromium...@chromium.org, prerendering-reviews, gavin...@chromium.org, tburkar...@chromium.org

Attention needed from Taiyo Mizuhashi

Lingqi Chi voted and added 1 comment

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+2

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File-level comment, Patchset 7 (Latest):

Lingqi Chi . resolved

let me submit this cl for now. Taiyo-san, plmk if you have any concerns.

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Chromium LUCI CQ (Gerrit)

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Jun 18, 2026, 9:42:27 PM (11 days ago) Jun 18

to Lingqi Chi, Hiroki Nakagawa, Taiyo Mizuhashi, chromium...@chromium.org, prerendering-reviews, gavin...@chromium.org, tburkar...@chromium.org

Chromium LUCI CQ submitted the change with unreviewed changes

Unreviewed changes

5 is the latest approved patch-set.
The change was submitted with unreviewed changes in the following files:

```
The name of the file: content/browser/preloading/prerender/prerender_browsertest.cc
Insertions: 6, Deletions: 5.

The diff is too large to show. Please review the diff.
```
```
The name of the file: content/browser/preloading/prerender/prerender_host.cc
Insertions: 5, Deletions: 7.

The diff is too large to show. Please review the diff.
```

Change information

Commit message:

[prerender] Allow prerendering pages to reuse initiator's process

This CL adds the basic implementation to allow prerendering pages to
reuse the initiator page's renderer process, for saving resources and
speeding up prerendering pages.

The implementation is behind a feature flag.
And follow-up CLs will restrict this feature to be used for same-site
pus pages only.

Bug: 524800804

Change-Id: I594986c53d56f7c7320621406a5ad8332190e6e0

Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/7950197

Commit-Queue: Lingqi Chi <lin...@chromium.org>

Reviewed-by: Hiroki Nakagawa <nhi...@chromium.org>

Cr-Commit-Position: refs/heads/main@{#1649452}

Files:

M content/browser/preloading/prerender/prerender_browsertest.cc
M content/browser/preloading/prerender/prerender_features.cc
M content/browser/preloading/prerender/prerender_features.h
M content/browser/preloading/prerender/prerender_host.cc

Change size: M

Delta: 4 files changed, 113 insertions(+), 0 deletions(-)

Branch: refs/heads/main

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[prerender] Allow prerendering pages to reuse initiator's process [chromium/src : main]

Lingqi Chi (Gerrit)

Lingqi Chi voted and added 1 comment

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Hiroki Nakagawa (Gerrit)

Hiroki Nakagawa voted and added 5 comments

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Lingqi Chi (Gerrit)

Lingqi Chi voted and added 5 comments

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Lingqi Chi (Gerrit)

Lingqi Chi voted and added 1 comment

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Chromium LUCI CQ (Gerrit)

Chromium LUCI CQ submitted the change with unreviewed changes

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