Ensure that PPAPI requests send `Sec-Fetch-Dest: embed`

Currently, we're sending `Sec-Fetch-Dest: unknown` for PPAPI-driven
requests. We ought to be sending `embed` or `object`.

This patch adds some tests to ensure that we're setting the context
for PPAPI requests to PLUGIN, and changes Blink's behavior to report
PLUGIN as `embed`. We ought to be distinguishing between `embed` and
`object`, but don't currently have the context when creating the
request to make that possible (and "embed" is strictly better than
"unknown" :) ).

Bug: 1021432
Change-Id: Ie0d2dff1dee85e34c2fab6f7ea2e542fede644e6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1899446Reviewed-by: Bill Budge <bbudge@chromium.org>
Commit-Queue: Mike West <mkwst@chromium.org>
Cr-Commit-Position: refs/heads/master@{#712911}

content/renderer/pepper/pepper_url_loader_host.cc

@@ -251,10 +251,10 @@ int32_t PepperURLLoaderHost::InternalOnHostMsgOpen(
     return PP_ERROR_FAILED;
   }
 
-  web_request.SetRequestContext(blink::mojom::RequestContextType::PLUGIN);
-
-  // Requests from plug-ins must skip service workers, see the comment in
-  // CreateWebURLRequest.
+  // Requests from plug-ins must be marked as PLUGIN, and must skip service
+  // workers, see the comment in CreateWebURLRequest.
+  DCHECK_EQ(blink::mojom::RequestContextType::PLUGIN,
+            web_request.GetRequestContext());
   DCHECK(web_request.GetSkipServiceWorker());
 
   WebAssociatedURLLoaderOptions options;

content/renderer/pepper/pepper_url_request_unittest.cc

@@ -68,6 +68,14 @@ class URLRequestInfoTest : public RenderViewTest {
     return web_request.HttpMethod();
   }
 
+  blink::mojom::RequestContextType GetContext() {
+    WebURLRequest web_request;
+    URLRequestInfoData data = info_->GetData();
+    if (!CreateWebURLRequest(pp_instance_, &data, GetMainFrame(), &web_request))
+      return blink::mojom::RequestContextType::UNSPECIFIED;
+    return web_request.GetRequestContext();
+  }
+
   WebString GetHeaderValue(const char* field) {
     WebURLRequest web_request;
     URLRequestInfoData data = info_->GetData();
@@ -206,6 +214,11 @@ TEST_F(URLRequestInfoTest, SetHeaders) {
   EXPECT_STREQ("baz", GetHeaderValue("bar").Utf8().data());
 }
 
+TEST_F(URLRequestInfoTest, RequestContext) {
+  // Test context is PLUGIN.
+  EXPECT_EQ(blink::mojom::RequestContextType::PLUGIN, GetContext());
+}
+
 // TODO(bbudge) Unit tests for AppendDataToBody, AppendFileToBody.
 
 }  // namespace content

content/renderer/pepper/url_request_info_util.cc

@@ -248,6 +248,8 @@ bool CreateWebURLRequest(PP_Instance instance,
     dest->SetExtraData(std::move(extra_data));
   }
 
+  dest->SetRequestContext(blink::mojom::RequestContextType::PLUGIN);
+
   return true;
 }
 

third_party/blink/common/loader/request_destination.cc

@@ -61,8 +61,14 @@ const char* GetRequestDestinationFromContext(
       return "xslt";
     case mojom::RequestContextType::IMPORT:
     case mojom::RequestContextType::INTERNAL:
-    case mojom::RequestContextType::PLUGIN:
       return "unknown";
+
+    // TODO(mkwst): We don't currently distinguish between plugin content loaded
+    // via `<embed>` or `<object>` as https://github.com/whatwg/fetch/pull/948
+    // asks us to do. See `content::PepperURLLoaderHost::InternalOnHostMsgOpen`
+    // for details.
+    case mojom::RequestContextType::PLUGIN:
+      return "embed";
   }
   NOTREACHED();
   return "";