linux: Pass subpixel positioning setting to WebKit.

content/browser/renderer_host/render_sandbox_host_linux.cc

Index: content/browser/renderer_host/render_sandbox_host_linux.cc
diff --git a/content/browser/renderer_host/render_sandbox_host_linux.cc b/content/browser/renderer_host/render_sandbox_host_linux.cc
index 8681ddd2fe4a250820bc520b5978e79aa93be595..3685a89e8b513e74fd1ab6cc13c149daa7e3f906 100644
--- a/content/browser/renderer_host/render_sandbox_host_linux.cc
+++ b/content/browser/renderer_host/render_sandbox_host_linux.cc
@@ -34,6 +34,7 @@
 #include "third_party/npapi/bindings/npapi_extensions.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebKit.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/linux/WebFontInfo.h"
+#include "ui/base/ui_base_switches.h"
 
 using WebKit::WebCString;
 using WebKit::WebFontInfo;
@@ -62,6 +63,12 @@ class SandboxIPCProcess  {
       sandbox_cmd_.push_back(sandbox_cmd);
       sandbox_cmd_.push_back(base::kFindInodeSwitch);
     }
+
+    // FontConfig doesn't provide a standard property to control subpixel
+    // positioning, so we pass a UI flag through to WebKit.
+    WebFontInfo::setSubpixelPositioning(
+        CommandLine::ForCurrentProcess()->HasSwitch(
+            switches::kEnableTextSubpixelPositioning));

[tony, 2012/06/06 23:43:16]

How does this command line switch get set on the sandbox IPC process?

[Daniel Erat, 2012/06/07 00:13:34]

That's a good question (for Adam). :-)  It seems to work.  Markus wasn't sure
where this code is running when I asked him.

[agl, 2012/06/07 21:55:24]

I have no idea either. How does this even compile? There's no 
setSubpixelPositioning function added in this CL. Is it a WebKit change?

(After syncing WebKit)

Ok, I see it. Yea, seems like it should work.

   }
 
   ~SandboxIPCProcess();
@@ -300,7 +307,8 @@ class SandboxIPCProcess  {
     reply.WriteInt(style.useHinting);
     reply.WriteInt(style.hintStyle);
     reply.WriteInt(style.useAntiAlias);
-    reply.WriteInt(style.useSubpixel);
+    reply.WriteInt(style.useSubpixelRendering);
+    reply.WriteInt(style.useSubpixelPositioning);
 
     SendRendererReply(fds, reply, -1);
   }