Fix reading PDF images from NSPasteboard.

ui/base/clipboard/clipboard_mac.mm

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/base/clipboard/clipboard_mac.h"
 
 #import <Cocoa/Cocoa.h>
 #include <stdint.h>
 
 #include <limits>
@@ skipping 306 matching lines @@
         image.reset([[NSImage alloc]
             initWithContentsOfURL:[NSURL fileURLWithPath:[paths lastObject]]]);
       }
     } else {
       if (pb)
         image.reset([[NSImage alloc] initWithPasteboard:pb]);
     }
   } @catch (id exception) {
   }
 
-  if (image.get()) {
-    if ([[image representations] count] == 1u) {
-      NSImageRep* rep = [[image representations] objectAtIndex:0];
+  if (!image)
+    return SkBitmap();
+  if ([[image representations] count] == 0u)
+    return SkBitmap();
+
+  // This logic prevents loss of pixels from retina images, where size != pixel
+  // size. In an ideal world, the concept of "retina-ness" would be plumbed all
+  // the way through to the web, but the clipboard API doesn't support the
+  // additional metainformation.
+  if ([[image representations] count] == 1u) {
+    NSImageRep* rep = [[image representations] objectAtIndex:0];
+    NSInteger width = [rep pixelsWide];
+    NSInteger height = [rep pixelsHigh];
+    if (width != 0 && height != 0) {
       return skia::NSImageRepToSkBitmapWithColorSpace(
-          rep, NSMakeSize([rep pixelsWide], [rep pixelsHigh]),
-          /*is_opaque=*/false, base::mac::GetSystemColorSpace());
+          rep, NSMakeSize(width, height), /*is_opaque=*/false,
+          base::mac::GetSystemColorSpace());
     }
-    return skia::NSImageToSkBitmapWithColorSpace(
-        image.get(), /*is_opaque=*/false, base::mac::GetSystemColorSpace());
   }
-  return SkBitmap();
+  return skia::NSImageToSkBitmapWithColorSpace(
+      image.get(), /*is_opaque=*/false, base::mac::GetSystemColorSpace());
 }
 
 SkBitmap ClipboardMac::ReadImage(ClipboardType type) const {
   return ReadImage(type, GetPasteboard());
 }
 
 void ClipboardMac::ReadCustomData(ClipboardType clipboard_type,
                                   const base::string16& type,
                                   base::string16* result) const {
   DCHECK(CalledOnValidThread());
@@ skipping 115 matching lines @@
 // Write an extra flavor that signifies WebKit was the last to modify the
 // pasteboard. This flavor has no data.
 void ClipboardMac::WriteWebSmartPaste() {
   NSPasteboard* pb = GetPasteboard();
   NSString* format = GetWebKitSmartPasteFormatType().ToNSString();
   [pb addTypes:[NSArray arrayWithObject:format] owner:nil];
   [pb setData:nil forType:format];
 }
 
 }  // namespace ui