Remove duplicate typedef

ui/surface/transport_dib_win.cc

Index: ui/surface/transport_dib_win.cc
diff --git a/ui/surface/transport_dib_win.cc b/ui/surface/transport_dib_win.cc
index 82eabf878785e51f74f000ecfc2acf8e8f075235..f002f55536d47251aa342e129a12eecfb3ed8d9e 100644
--- a/ui/surface/transport_dib_win.cc
+++ b/ui/surface/transport_dib_win.cc
@@ -58,7 +58,7 @@ bool TransportDIB::is_valid_handle(Handle dib) {
   return dib.IsValid();
 }
 
-skia::PlatformCanvas* TransportDIB::GetPlatformCanvas(int w, int h,
+SkCanvas* TransportDIB::GetPlatformCanvas(int w, int h,
                                                       bool opaque) {
   // This DIB already mapped the file into this process, but PlatformCanvas
   // will map it again.
@@ -67,7 +67,7 @@ skia::PlatformCanvas* TransportDIB::GetPlatformCanvas(int w, int h,
   // We can't check the canvas size before mapping, but it's safe because
   // Windows will fail to map the section if the dimensions of the canvas
   // are too large.
-  skia::PlatformCanvas* canvas = skia::CreatePlatformCanvas(
+  SkCanvas* canvas = skia::CreatePlatformCanvas(
       w, h, opaque, shared_memory_.handle().GetHandle(),
       skia::RETURN_NULL_ON_FAILURE);