BrowserFontResource should not push opacity info to Blink

content/child/browser_font_resource_trusted.cc

Index: content/child/browser_font_resource_trusted.cc
diff --git a/content/child/browser_font_resource_trusted.cc b/content/child/browser_font_resource_trusted.cc
index 9450a001ebedda023a69994d881e5007330d7226..2244bafc7ecda4376cecccf56328d80d446918fe 100644
--- a/content/child/browser_font_resource_trusted.cc
+++ b/content/child/browser_font_resource_trusted.cc
@@ -24,6 +24,7 @@
 #include "third_party/WebKit/public/web/WebTextRun.h"
 #include "third_party/icu/source/common/unicode/ubidi.h"
 #include "third_party/skia/include/core/SkRect.h"
+#include "third_party/skia/include/effects/SkPaintFlagsDrawFilter.h"
 
 using ppapi::StringVar;
 using ppapi::thunk::EnterResourceNoLock;
@@ -409,13 +410,24 @@ void BrowserFontResource_Trusted::DrawTextToCanvas(
                        clip->size.width, clip->size.height);
   }
 
+  SkAutoCanvasRestore auto_restore(destination, false);
+  if (!PP_ToBool(image_data_is_opaque)) {
+    // Ideally, LCD text should be configured at canvas creation time using
+    // SkSurfaceProps. But because the API exposes image_data_is_opaque per
+    // draw text call (allowing clients to essentially change their mind),
+    // we have to handle it here.
+    destination->save();

[reed1, 2015/03/03 15:04:42]

save(); // will be balanced automatically by auto_restore above...

+    skia::RefPtr<SkDrawFilter> lcd_filter = skia::AdoptRef(
+        new SkPaintFlagsDrawFilter(SkPaint::kLCDRenderText_Flag, 0));
+    destination->setDrawFilter(lcd_filter.get());
+  }
+
   TextRunCollection runs(text);
   for (int i = 0; i < runs.num_runs(); i++) {
     int32_t run_begin = 0;
     int32_t run_len = 0;
     WebTextRun run = runs.GetRunAt(i, &run_begin, &run_len);
-    font_->drawText(destination, run, web_position, color, web_clip,
-                    PP_ToBool(image_data_is_opaque));
+    font_->drawText(destination, run, web_position, color, web_clip);
 
     // Advance to the next run. Note that we avoid doing this for the last run
     // since it's unnecessary, measuring text is slow, and most of the time