Add file icons to chrome://downloads/ on the Mac. Add Skia helper CGImageToSkBitmap().

chrome/browser/icon_loader_mac.mm

Index: chrome/browser/icon_loader_mac.mm
diff --git a/chrome/browser/icon_loader_mac.mm b/chrome/browser/icon_loader_mac.mm
index 83a8305df72992896035ca2095dd07276051ba56..744b6cb338c83f6805db5c886194f6732fff7aa6 100644
--- a/chrome/browser/icon_loader_mac.mm
+++ b/chrome/browser/icon_loader_mac.mm
@@ -4,11 +4,28 @@
 
 #include "chrome/browser/icon_loader.h"
 
+#import <AppKit/AppKit.h>
+
 #include "base/message_loop.h"
 #include "base/thread.h"
+#include "base/sys_string_conversions.h"
+#include "skia/ext/skia_utils_mac.h"
+#include "third_party/skia/include/core/SkBitmap.h"
 
 void IconLoader::ReadIcon() {
-  NOTIMPLEMENTED();
+  NSString* group = base::SysUTF8ToNSString(group_);
+  NSWorkspace* workspace = [NSWorkspace sharedWorkspace];
+  NSImage* icon = [workspace iconForFileType:group];
+  
+  NSSize size;
+  if (icon_size_ == NORMAL)
+    size = NSMakeSize(32, 32);
+  else if (icon_size_ == SMALL)
+    size = NSMakeSize(16, 16);
+  else
+    return;
+  
+  bitmap_ = new SkBitmap(gfx::NSImageToSkBitmap(icon, size, false));
 
   target_message_loop_->PostTask(FROM_HERE,
       NewRunnableMethod(this, &IconLoader::NotifyDelegate));