Improving GestureNav screenshotting performance - part 2 - GestureNav

content/browser/frame_host/navigation_entry_screenshot_manager.cc

Index: content/browser/frame_host/navigation_entry_screenshot_manager.cc
diff --git a/content/browser/frame_host/navigation_entry_screenshot_manager.cc b/content/browser/frame_host/navigation_entry_screenshot_manager.cc
index 4c521176058025bb2d40fdfc1af08dbff6454379..9a038f7e72ee62d03ad8557db7855d2aa1d1e0ee 100644
--- a/content/browser/frame_host/navigation_entry_screenshot_manager.cc
+++ b/content/browser/frame_host/navigation_entry_screenshot_manager.cc
@@ -13,9 +13,6 @@
 #include "content/public/browser/render_widget_host.h"
 #include "content/public/browser/render_widget_host_view.h"
 #include "content/public/common/content_switches.h"
-#include "third_party/skia/include/core/SkCanvas.h"
-#include "third_party/skia/include/core/SkPaint.h"
-#include "third_party/skia/include/effects/SkLumaColorFilter.h"
 #include "ui/gfx/codec/png_codec.h"
 
 namespace {
@@ -52,18 +49,10 @@ class ScreenshotData : public base::RefCountedThreadSafe<ScreenshotData> {
   }
 
   void EncodeOnWorker(const SkBitmap& bitmap) {
+    DCHECK_EQ(bitmap.colorType(), kAlpha_8_SkColorType);
+    // Encode the A8 bitmap to grayscale PNG treating alpha as color intensity.
     std::vector<unsigned char> data;
-    // Paint |bitmap| to a kAlpha_8_SkColorType SkBitmap
-    SkBitmap a8Bitmap;
-    a8Bitmap.allocPixels(SkImageInfo::MakeA8(bitmap.width(), bitmap.height()));
-    SkCanvas canvas(a8Bitmap);
-    SkPaint paint;
-    SkColorFilter* filter = SkLumaColorFilter::Create();
-    paint.setColorFilter(filter);
-    filter->unref();
-    canvas.drawBitmap(bitmap, SkIntToScalar(0), SkIntToScalar(0), &paint);
-    // Encode the a8Bitmap to grayscale PNG treating alpha as color intensity
-    if (gfx::PNGCodec::EncodeA8SkBitmap(a8Bitmap, &data))
+    if (gfx::PNGCodec::EncodeA8SkBitmap(bitmap, &data))
       data_ = new base::RefCountedBytes(data);
   }
 
@@ -130,14 +119,13 @@ void NavigationEntryScreenshotManager::TakeScreenshotImpl(
     NavigationEntryImpl* entry) {
   DCHECK(host && host->GetView());
   DCHECK(entry);
-  SkColorType preferred_format = host->PreferredReadbackFormat();
   host->CopyFromBackingStore(
       gfx::Rect(),
       host->GetView()->GetViewBounds().size(),
       base::Bind(&NavigationEntryScreenshotManager::OnScreenshotTaken,
                  screenshot_factory_.GetWeakPtr(),
                  entry->GetUniqueID()),
-      preferred_format);
+      kAlpha_8_SkColorType);
 }
 
 void NavigationEntryScreenshotManager::SetMinScreenshotIntervalMS(