Ensure MimeHandlerView plugins load properly with long URLs

Currently if a URL which is handled by a MimeHandlerView is too long,
mojo will refuse to send the string inside the StreamDetails which are sent to
the renderer. In these cases we truncate the URL which gets sent.

BUG=478389

Review URL: https://codereview.chromium.org/1062283003

Cr-Commit-Position: refs/heads/master@{#326468}
(cherry picked from commit b9a01b5)

Review URL: https://codereview.chromium.org/1109693002

Cr-Commit-Position: refs/branch-heads/2357@{#234}
Cr-Branched-From: 59d4494-refs/heads/master@{#323860}

Author: Raymes Khoury

chrome/test/data/extensions/api_test/mime_handler_view/index.js

@@ -38,6 +38,11 @@ function expectSuccessfulRead(response) {
   chrome.test.assertEq('content to read\n', response.data);
 }
 
+function expectSuccessfulReadLong(response) {
+  chrome.test.assertEq(200, response.status);
+  chrome.test.assertTrue(response.data.indexOf('content to read\n') === 0);
+}
+
 function checkStreamDetails(name, embedded) {
   checkStreamDetailsNoFile();
   chrome.test.assertEq(embedded, streamDetails.embedded);
@@ -128,6 +133,13 @@ var tests = [
     fetchUrl(streamDetails.streamUrl)
         .then(expectSuccessfulRead)
         .then(chrome.test.succeed);
+  },
+
+  function testDataUrlLong() {
+    checkStreamDetailsNoFile();
+    fetchUrl(streamDetails.streamUrl)
+        .then(expectSuccessfulReadLong)
+        .then(chrome.test.succeed);
   }
 ];
 
@@ -153,6 +165,10 @@ chrome.mimeHandlerPrivate.getStreamInfo(function(streamInfo) {
   // Run the test for data URLs.
   if (streamInfo.originalUrl.indexOf("data:") === 0) {
     window.removeEventListener('message', queueMessage);
-    chrome.test.runTests([testsByName['testDataUrl']]);
+    // Long data URLs get truncated.
+    if (streamInfo.originalUrl == "data:")
+      chrome.test.runTests([testsByName['testDataUrlLong']]);
+    else
+      chrome.test.runTests([testsByName['testDataUrl']]);
   }
 });

chrome/test/data/extensions/api_test/mime_handler_view/test_embedded_data_url_long.html

@@ -7,6 +7,7 @@
 #include "base/strings/string_util.h"
 #include "content/public/browser/stream_handle.h"
 #include "content/public/browser/stream_info.h"
+#include "content/public/common/content_constants.h"
 #include "extensions/browser/guest_view/mime_handler_view/mime_handler_view_guest.h"
 #include "extensions/common/constants.h"
 #include "net/http/http_response_headers.h"
@@ -99,7 +100,18 @@ extensions::mime_handler::StreamInfoPtr TypeConverter<
   result->tab_id = stream.tab_id();
   const content::StreamInfo* info = stream.stream_info();
   result->mime_type = info->mime_type;
-  result->original_url = info->original_url.spec();
+
+  // If the URL is too long, mojo will give up on sending the URL. In these
+  // cases truncate it. Only data: URLs should ever really suffer this problem
+  // so only worry about those for now.
+  // TODO(raymes): This appears to be a bug in mojo somewhere. crbug.com/480099.
+  if (info->original_url.SchemeIs(url::kDataScheme) &&
+      info->original_url.spec().size() > content::kMaxURLDisplayChars) {
+    result->original_url = info->original_url.scheme() + ":";
+  } else {
+    result->original_url = info->original_url.spec();
+  }
+
   result->stream_url = info->handle->GetURL().spec();
   result->response_headers =
       extensions::CreateResponseHeadersMap(info->response_headers.get());

extensions/browser/api/mime_handler_private/mime_handler_private.cc

@@ -86,3 +86,7 @@ IN_PROC_BROWSER_TEST_F(MimeHandlerViewTest, EmbeddedDataUrlObject) {
 IN_PROC_BROWSER_TEST_F(MimeHandlerViewTest, EmbeddedDataUrlEmbed) {
   RunTest("test_embedded_data_url_embed.html");
 }
+
+IN_PROC_BROWSER_TEST_F(MimeHandlerViewTest, EmbeddedDataUrlLong) {
+  RunTest("test_embedded_data_url_long.html");
+}