webui: minimize webui flicker.

content/browser/webui/shared_resources_data_source.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/webui/shared_resources_data_source.h"
 
 #include "base/logging.h"
 #include "base/memory/ref_counted_memory.h"
+#include "base/strings/string_piece.h"
 #include "base/strings/string_util.h"
 #include "base/threading/thread_restrictions.h"
 #include "content/public/common/content_client.h"
 #include "content/public/common/url_constants.h"
 #include "net/base/mime_util.h"
+#include "ui/base/layout.h"
+#include "ui/resources/grit/webui_resources.h"
 #include "ui/resources/grit/webui_resources_map.h"
 
+namespace content {
+
 namespace {
 
 const char kAppImagesPath[] = "images/apps/";
 const char kAppImagesPath2x[] = "images/2x/apps/";
 
 const char kReplacement[] = "../../resources/default_100_percent/common/";
 const char kReplacement2x[] = "../../resources/default_200_percent/common/";
 
 // This entire method is a hack introduced to be able to handle apps images
 // that exist in the ui/resources directory. From JS/CSS, we still load the
@@ skipping 30 matching lines @@
 
 }  // namespace
 
 SharedResourcesDataSource::SharedResourcesDataSource() {
 }
 
 SharedResourcesDataSource::~SharedResourcesDataSource() {
 }
 
 std::string SharedResourcesDataSource::GetSource() const {
-  return content::kChromeUIResourcesHost;
+  return kChromeUIResourcesHost;
 }
 
 void SharedResourcesDataSource::StartDataRequest(
     const std::string& path,
     int render_process_id,
     int render_frame_id,
-    const content::URLDataSource::GotDataCallback& callback) {
+    const URLDataSource::GotDataCallback& callback) {
   int idr = PathToIDR(path);
   DCHECK_NE(-1, idr) << " path: " << path;
-  scoped_refptr<base::RefCountedStaticMemory> bytes(
-      content::GetContentClient()->GetDataResourceBytes(idr));
+  scoped_refptr<base::RefCountedMemory> bytes;
+
+  ContentClient* content_client = GetContentClient();
+  if (idr == IDR_WEBUI_CSS_TEXT_DEFAULTS) {

[davidben, 2014/11/25 22:29:34]

It is also a little puzzling to me why this hooks in here rather than in some
embedder-supplied code that defines the path appropriately. But I'm not very
familiar with all our data resource mechanisms, so that might not work very
well.

[Dan Beam, 2014/11/25 22:49:31]

creis@ nor I know the preferred mechanism here (path vs. idr).  I've added a
TODO() and will bug jam@ about it when he gets back next week.

+    std::vector<std::string> placeholders;
+    WebUITextStyles text_styles = content_client->GetWebUITextStyles();
+    placeholders.push_back(text_styles.text_direction);  // $1
+    placeholders.push_back(text_styles.font_family);  // $2
+    placeholders.push_back(text_styles.font_size);  // $3
+
+    const std::string& chrome_shared =
+        content_client->GetDataResource(idr, ui::SCALE_FACTOR_NONE).as_string();
+    std::string replaced =
+        ReplaceStringPlaceholders(chrome_shared, placeholders, nullptr);
+    bytes = base::RefCountedString::TakeString(&replaced);
+  } else {
+    bytes = content_client->GetDataResourceBytes(idr);
+  }
 
   callback.Run(bytes.get());
 }
 
 std::string SharedResourcesDataSource::GetMimeType(
     const std::string& path) const {
   // Requests should not block on the disk!  On POSIX this goes to disk.
   // http://code.google.com/p/chromium/issues/detail?id=59849
 
   base::ThreadRestrictions::ScopedAllowIO allow_io;
   std::string mime_type;
   net::GetMimeTypeFromFile(base::FilePath().AppendASCII(path), &mime_type);
   return mime_type;
 }
 
 std::string
 SharedResourcesDataSource::GetAccessControlAllowOriginForOrigin(
     const std::string& origin) const {
   // For now we give access only for "chrome://*" origins.
   // According to CORS spec, Access-Control-Allow-Origin header doesn't support
   // wildcards, so we need to set its value explicitly by passing the |origin|
   // back.
-  std::string allowed_origin_prefix = content::kChromeUIScheme;
+  std::string allowed_origin_prefix = kChromeUIScheme;
   allowed_origin_prefix += "://";
   if (origin.find(allowed_origin_prefix) != 0)
     return "none";
   return origin;
 }
+
+}  // namespace content