Make gfx::Rect class operations consistently mutate the class they are called on.

webkit/plugins/ppapi/ppb_graphics_2d_impl.cc

Index: webkit/plugins/ppapi/ppb_graphics_2d_impl.cc
diff --git a/webkit/plugins/ppapi/ppb_graphics_2d_impl.cc b/webkit/plugins/ppapi/ppb_graphics_2d_impl.cc
index 85c27d96a47feca1589f15814fa79c80aa08a782..923b88d4af73f2d488f800ba278162d082ba5df5 100644
--- a/webkit/plugins/ppapi/ppb_graphics_2d_impl.cc
+++ b/webkit/plugins/ppapi/ppb_graphics_2d_impl.cc
@@ -376,7 +376,8 @@ int32_t PPB_Graphics2D_Impl::Flush(scoped_refptr<TrackedCallback> callback,
 
       // Set |no_update_visible| to false if the change overlaps the visible
       // area.
-      gfx::Rect visible_changed_rect = clip.Intersect(op_rect);
+      gfx::Rect visible_changed_rect = clip;
+      visible_changed_rect.Intersect(op_rect);
       if (!visible_changed_rect.IsEmpty())
         no_update_visible = false;
 
@@ -560,7 +561,8 @@ void PPB_Graphics2D_Impl::Paint(WebKit::WebCanvas* canvas,
 
   CGContextDrawImage(canvas, bitmap_rect, image);
 #else
-  gfx::Rect invalidate_rect = plugin_rect.Intersect(paint_rect);
+  gfx::Rect invalidate_rect = plugin_rect;
+  invalidate_rect.Intersect(paint_rect);
   SkRect sk_invalidate_rect = gfx::RectToSkRect(invalidate_rect);
   SkAutoCanvasRestore auto_restore(canvas, true);
   canvas->clipRect(sk_invalidate_rect);
@@ -647,12 +649,17 @@ bool PPB_Graphics2D_Impl::ConvertToLogicalPixels(float scale,
   // Take the enclosing rectangle after scaling so a rectangle scaled down then
   // scaled back up by the inverse scale would fully contain the entire area
   // affected by the original rectangle.
-  *op_rect = gfx::ToEnclosingRect(op_rect->Scale(scale));
+  gfx::RectF scaled_rect = *op_rect;
+  scaled_rect.Scale(scale);
+  *op_rect = gfx::ToEnclosingRect(scaled_rect);
   if (delta) {
     gfx::Point original_delta = *delta;
     float inverse_scale = 1.0f / scale;
     *delta = gfx::ToFlooredPoint(delta->Scale(scale));
-    if (original_rect != gfx::ToEnclosingRect(op_rect->Scale(inverse_scale)) ||
+
+    gfx::RectF inverse_scaled_rect = *op_rect;
+    inverse_scaled_rect.Scale(inverse_scale);
+    if (original_rect != gfx::ToEnclosingRect(inverse_scaled_rect) ||
         original_delta != gfx::ToFlooredPoint(delta->Scale(inverse_scale))) {
       return false;
     }