Create a private API for controlling WebRTC's AEC3

chrome/browser/extensions/api/webrtc_audio_private/webrtc_audio_private_api.cc

Index: chrome/browser/extensions/api/webrtc_audio_private/webrtc_audio_private_api.cc
diff --git a/chrome/browser/extensions/api/webrtc_audio_private/webrtc_audio_private_api.cc b/chrome/browser/extensions/api/webrtc_audio_private/webrtc_audio_private_api.cc
index baf803d0bb7d4bdabe86ab932f74c27d6af63844..76fb27d079953a8b050bae3d340c7b25b176026c 100644
--- a/chrome/browser/extensions/api/webrtc_audio_private/webrtc_audio_private_api.cc
+++ b/chrome/browser/extensions/api/webrtc_audio_private/webrtc_audio_private_api.cc
@@ -4,12 +4,14 @@
 
 #include "chrome/browser/extensions/api/webrtc_audio_private/webrtc_audio_private_api.h"
 
+#include <memory>
 #include <utility>
 #include <vector>
 
 #include "base/lazy_instance.h"
 #include "base/memory/ptr_util.h"
 #include "base/strings/string_number_conversions.h"
+#include "base/strings/stringprintf.h"
 #include "base/task_runner_util.h"
 #include "chrome/browser/extensions/api/tabs/tabs_constants.h"
 #include "chrome/browser/extensions/extension_tab_util.h"
@@ -217,6 +219,45 @@ std::string WebrtcAudioPrivateFunction::device_id_salt() const {
   return device_id_salt_;
 }
 
+// TODO(hlundin): Stolen from WebrtcLoggingPrivateFunction. Maybe consolidate?
+content::RenderProcessHost* WebrtcAudioPrivateFunction::RphFromRequest(
+    const RequestInfo& request,
+    const std::string& security_origin) {
+  // If |guest_process_id| is defined, directly use this id to find the
+  // corresponding RenderProcessHost.
+  if (request.guest_process_id.get())

[Devlin, 2017/04/10 21:34:24]

nit: no need for .get() (same for below)

[hlundin-chromium, 2017/04/11 09:19:37]

Done.

+    return content::RenderProcessHost::FromID(*request.guest_process_id);
+
+  // Otherwise, use the |tab_id|. If there's no |tab_id| and no
+  // |guest_process_id|, we can't look up the RenderProcessHost.
+  if (!request.tab_id.get()) {
+    error_ = "No tab ID or guest process ID specified.";
+    return nullptr;
+  }
+
+  int tab_id = *request.tab_id;
+  content::WebContents* contents = nullptr;
+  if (!ExtensionTabUtil::GetTabById(tab_id, GetProfile(), true, nullptr,
+                                    nullptr, &contents, nullptr)) {
+    error_ = extensions::ErrorUtils::FormatErrorMessage(

[Devlin, 2017/04/10 21:34:24]

GetTabById() will populate this error for you if you pass it in.

[hlundin-chromium, 2017/04/11 09:19:37]

Iiuc, this is only true for the version of GetTabById that is defined in
https://cs.chromium.org/chromium/src/chrome/browser/extensions/api/tabs/tabs_...,
which is in an unnamed namespace in that file. So I cannot use it here.

+        extensions::tabs_constants::kTabNotFoundError,
+        base::IntToString(tab_id));
+    return nullptr;
+  }
+  if (!contents) {

[Devlin, 2017/04/10 21:34:25]

This should never happen if GetTabById() succeeds.  If you want some assertion
here, you could [D]CHECK(web_contents), but there shouldn't need to be a branch.

[Henrik Grunell, 2017/04/11 06:49:39]

Good to know, thanks. Henrik L, remove this block completely. Dereference on
next line will act as a check.

[hlundin-chromium, 2017/04/11 09:19:37]

Done.

+    error_ = "Web contents for tab not found.";
+    return nullptr;
+  }
+  GURL expected_origin = contents->GetLastCommittedURL().GetOrigin();
+  if (expected_origin.spec() != security_origin) {

[Devlin, 2017/04/10 21:34:24]

Using strings to compare origins is scary for lots of reasons.  Can we instead
use the url libraries?

[Henrik Grunell, 2017/04/11 06:49:39]

Exactly which way do you suggest to compare? Origin::IsSameOriginWith()?

Note that the security origin to compare with is given as a string by the
extension. This is an existing design.

Given that this code is taken from another extension API (see comment before
function), I suggest leaving this as is for now, file a bug for changing this in
both places (and probably consolidate the two functions). A simple change is of
course fine.

[hlundin-chromium, 2017/04/11 09:19:37]

I filed a bug and added to the TODO.

+    error_ = base::StringPrintf(
+        "Invalid security origin. Expected=%s, actual=%s",
+        expected_origin.spec().c_str(), security_origin.c_str());
+    return nullptr;
+  }
+  return contents->GetRenderProcessHost();
+}
+
 bool WebrtcAudioPrivateGetSinksFunction::RunAsync() {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
 
@@ -504,4 +545,31 @@ void WebrtcAudioPrivateGetAssociatedSinkFunction::OnHMACCalculated(
   SendResponse(true);
 }
 
+WebrtcAudioPrivateSetAudioExperimentsFunction::
+    WebrtcAudioPrivateSetAudioExperimentsFunction() {}
+
+WebrtcAudioPrivateSetAudioExperimentsFunction::
+    ~WebrtcAudioPrivateSetAudioExperimentsFunction() {}
+
+bool WebrtcAudioPrivateSetAudioExperimentsFunction::RunAsync() {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+  std::unique_ptr<wap::SetAudioExperiments::Params> params(
+      wap::SetAudioExperiments::Params::Create(*args_));
+  EXTENSION_FUNCTION_VALIDATE(params.get());
+
+  if (params->audio_experiments.enable_aec3.get()) {
+    content::RenderProcessHost* host =
+        RphFromRequest(params->request, params->security_origin);
+    if (!host) {
+      SendResponse(false);
+      return false;
+    }
+
+    host->SetEchoCanceller3(*params->audio_experiments.enable_aec3);
+  }
+
+  SendResponse(true);
+  return true;
+}
+
 }  // namespace extensions