Fixes error thrown when speculation rules are disabled

[samartnik]

Resolves brave/brave-browser#23433

The error we hit is:
[ERROR:render_process_host_impl.cc(5119)] Terminating render process for bad Mojo message: Received bad user message: Speculation rules must be enabled to bind to blink.mojom.SpeculationHost in the browser.

Submitter Checklist:

• I confirm that no security/privacy review is needed, or that I have requested one
• There is a ticket for my issue
• Used Github auto-closing keywords in the PR description above
• Wrote a good PR/commit description
• Squashed any review feedback or "fixup" commits before merge, so that history is a record of what happened in the repo, not your PR
• Added appropriate labels (QA/Yes or QA/No; release-notes/include or release-notes/exclude; OS/...) to the associated issue
• Checked the PR locally: npm run test -- brave_browser_tests, npm run test -- brave_unit_tests, npm run lint, npm run gn_check, npm run tslint
• Ran git rebase master (if needed)

Reviewer Checklist:

• A security review is not needed, or a link to one is included in the PR description
• New files have MPL-2.0 license header
• Adequate test coverage exists to prevent regressions
• Major classes, functions and non-trivial code blocks are well-commented
• Changes in component dependencies are properly reflected in gn
• Code follows the style guide
• Test plan is specified in PR before merging

After-merge Checklist:

• The associated issue milestone is set to the smallest version that the
  changes has landed on
• All relevant documentation has been updated, for instance:
  • https://github.com/brave/brave-browser/wiki/Deviations-from-Chromium-(features-we-disable-or-remove)
  • https://github.com/brave/brave-browser/wiki/Proxy-redirected-URLs
  • https://github.com/brave/brave-browser/wiki/Fingerprinting-Protections
  • https://github.com/brave/brave-browser/wiki/Brave%E2%80%99s-Use-of-Referral-Codes
  • https://github.com/brave/brave-browser/wiki/Custom-Headers
  • https://github.com/brave/brave-browser/wiki/Web-Compatibility-Exceptions-in-Brave
  • https://github.com/brave/brave-browser/wiki/QA-Guide
  • https://github.com/brave/brave-browser/wiki/P3A

Test Plan:

[goodov]

maybe we should fix brave/chromium_src/third_party/blink/common/origin_trials/origin_trials.cc instead?

[samartnik]

@goodov cloud you elaborate? What fix can be applied there?

[goodov]

I'm not sure right now, but adding SpeculationRulesPrefetchProxy into the list of disabled features in origin_trials.cc won't fix the issue? (there're two lists)
It looks like the feature is partially disabled now. Because of that we see this incorrect request on the browser side.

[samartnik]

We should probably add kSpeculationRulesPrefetchProxy there either way, but it doesn't fix error. We still hit it.

[samartnik]

Just to be more specific, this change doesn't help

--- a/chromium_src/third_party/blink/common/origin_trials/origin_trials.cc
+++ b/chromium_src/third_party/blink/common/origin_trials/origin_trials.cc
@@ -35,6 +35,7 @@ bool IsTrialDisabledInBrave(base::StringPiece trial_name) {
       "Prerender2",
       "PrivacySandboxAdsAPIs",
       "SignedExchangeSubresourcePrefetch",
+      "SpeculationRulesPrefetch",
       "SubresourceWebBundles",
       "TrustTokens",
   };
@@ -65,6 +66,7 @@ bool IsTrialDisabledInBrave(OriginTrialFeature feature) {
           OriginTrialFeature::kPrerender2,
           OriginTrialFeature::kPrivacySandboxAdsAPIs,
           OriginTrialFeature::kSignedExchangeSubresourcePrefetch,
+          OriginTrialFeature::kSpeculationRulesPrefetchProxy,
           OriginTrialFeature::kTrustTokens,
       };
   // clang-format on

[goodov]

ok. I'll try to figure out what's going on there with feature/trial disabling.

[goodov]

@samartnik a better fix is to remove this line: chromium/chromium@3c9efd5#diff-a800f352ae257f734b958312eedfc8fd15d26d50574ecc4c4e639b9a1d825df3R2197

I'm okay with patching it until we figure out what is the better way to do this without patches.

[samartnik]

So you want just directly patch it instead of chromium_src changes?

[goodov]

I think I've got a patchless solution. Put this file into brave/chromium_src/content/child/runtime_features.cc:
https://gist.github.com/goodov/a62434bb5e940b2f9f6b26e711bdc638

[goodov]

@samartnik Actually there is even a better place which already does exactly this:

brave-core/renderer/brave_content_renderer_client.cc

Lines 30 to 46 in 77a4b69

	void BraveContentRendererClient::
	SetRuntimeFeaturesDefaultsBeforeBlinkInitialization() {
	ChromeContentRendererClient::
	SetRuntimeFeaturesDefaultsBeforeBlinkInitialization();
	blink::WebRuntimeFeatures::EnableWebNfc(false);
	// These features don't have dedicated WebRuntimeFeatures wrappers.
	blink::WebRuntimeFeatures::EnableFeatureFromString("DigitalGoods", false);
	if (!base::FeatureList::IsEnabled(blink::features::kFileSystemAccessAPI)) {
	blink::WebRuntimeFeatures::EnableFeatureFromString("FileSystemAccess",
	false);
	blink::WebRuntimeFeatures::EnableFeatureFromString(
	"FileSystemAccessAPIExperimental", false);
	}
	blink::WebRuntimeFeatures::EnableFeatureFromString("Serial", false);
	}

Just add a single line with this exact feature right there and we should be fine. No need to add new source file.

[Uni-verse]

Verified on Samsung GS 21 & Tab S7 using

Brave	1.41.63 Chromium: 103.0.5060.42 (Official Build) canary (32-bit) 
Revision	de0d840bf9439c31bd86bf74f065c31fdf9b208d-refs/branch-heads/5060@{#667}
OS	Android 12; Build/SP1A.210812.016

STR - brave/brave-browser#23433 (comment)

• Confirmed search results are displayed when using search on google homepage.
• Confirmed user is able to search using key phrase and suggested trending searches.

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