android: Fix inconsistent sizes in GetScaledContentBitmap

content/browser/renderer_host/render_widget_host_view_android.cc

Index: content/browser/renderer_host/render_widget_host_view_android.cc
diff --git a/content/browser/renderer_host/render_widget_host_view_android.cc b/content/browser/renderer_host/render_widget_host_view_android.cc
index 644343df3754e8b8d962c298eb860135033e7536..a134b308b7be53b0c7be2e4676baad95a4f1ecb4 100644
--- a/content/browser/renderer_host/render_widget_host_view_android.cc
+++ b/content/browser/renderer_host/render_widget_host_view_android.cc
@@ -66,6 +66,7 @@
 #include "ui/gfx/android/device_display_info.h"
 #include "ui/gfx/android/java_bitmap.h"
 #include "ui/gfx/display.h"
+#include "ui/gfx/point_conversions.h"
 #include "ui/gfx/screen.h"
 #include "ui/gfx/size_conversions.h"
 
@@ -299,19 +300,32 @@ void RenderWidgetHostViewAndroid::GetScaledContentBitmap(
     return;
   }
 
-  gfx::Size bounds = layer_->bounds();
-  if (src_subrect.IsEmpty())
-    src_subrect = gfx::Rect(bounds);
-  DCHECK_LE(src_subrect.width() + src_subrect.x(), bounds.width());
-  DCHECK_LE(src_subrect.height() + src_subrect.y(), bounds.height());
   const gfx::Display& display =
       gfx::Screen::GetNativeScreen()->GetPrimaryDisplay();
   float device_scale_factor = display.device_scale_factor();
   DCHECK_GT(device_scale_factor, 0);
-  gfx::Size dst_size(
-      gfx::ToCeiledSize(gfx::ScaleSize(bounds, scale / device_scale_factor)));
+
+  gfx::Size bounds = layer_->bounds();
+
+  gfx::Size dst_size_in_dip(gfx::ToCeiledSize(gfx::ScaleSize(bounds, scale)));
+
+  gfx::RectF src_subrect_in_dip_f(gfx::ScaleRect(
+      ConvertRectToDIP(device_scale_factor, src_subrect), scale));

[no sievers, 2014/06/11 21:39:11]

Why does the src_subrect get scaled by |scale|?

[powei, 2014/06/11 21:46:12]

I think |src_subrect| assumes its space to be pre-scaled.  It's only used for
the NTP thumbnails.

+
+  gfx::Rect src_subrect_in_dip(
+      gfx::ToFlooredPoint(src_subrect_in_dip_f.origin()),
+      gfx::ToCeiledSize(src_subrect_in_dip_f.size()));
+
+  if (src_subrect_in_dip.IsEmpty())
+    src_subrect_in_dip = gfx::Rect(dst_size_in_dip);

[no sievers, 2014/06/11 21:39:11]

When does this happen?

[powei, 2014/06/11 21:46:11]

It's a somewhat hacky convention that when |src_subrect| is empty, then just
take the entire content.  Added here
(https://codereview.chromium.org/173023005/)  when we were fixing NTP thumbnails
and yet wanted to keep this method for tab switcher thumbnails.  So tab-switcher
thumbnails also pass in empty |src_subrect|s.

+
+  DCHECK_LE(src_subrect_in_dip.width() + src_subrect_in_dip.x(),
+            bounds.width());
+  DCHECK_LE(src_subrect_in_dip.height() + src_subrect_in_dip.y(),
+            bounds.height());
+
   CopyFromCompositingSurface(
-      src_subrect, dst_size, result_callback, bitmap_config);
+      src_subrect_in_dip, dst_size_in_dip, result_callback, bitmap_config);
 }
 
 bool RenderWidgetHostViewAndroid::HasValidFrame() const {