webui: minimize webui flicker.

content/browser/webui/shared_resources_data_source.cc

Index: content/browser/webui/shared_resources_data_source.cc
diff --git a/content/browser/webui/shared_resources_data_source.cc b/content/browser/webui/shared_resources_data_source.cc
index 2ce6e147b098dc598f75b2d7e0577de0256f26cb..0708094803d35e8419bc168454f5f6ec6599404d 100644
--- a/content/browser/webui/shared_resources_data_source.cc
+++ b/content/browser/webui/shared_resources_data_source.cc
@@ -6,13 +6,18 @@
 
 #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/";
@@ -63,18 +68,34 @@ 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());
 }
@@ -97,9 +118,11 @@ SharedResourcesDataSource::GetAccessControlAllowOriginForOrigin(
   // 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