Disallow multiple selection in desktop media picker.

chrome/browser/ui/cocoa/media_picker/desktop_media_picker_controller.mm

 // Copyright 2013 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.
 
 #import "chrome/browser/ui/cocoa/media_picker/desktop_media_picker_controller.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #import "base/mac/bundle_locations.h"
 #include "base/strings/sys_string_conversions.h"
@@ skipping 109 matching lines @@
   [content addSubview:description];
   origin.y += NSHeight([description frame]) + kControlSpacing;
 
   // Create the image browser.
   sourceBrowser_.reset([[IKImageBrowserView alloc] initWithFrame:NSZeroRect]);
   NSUInteger cellStyle = IKCellsStyleShadowed | IKCellsStyleTitled;
   [sourceBrowser_ setDelegate:self];
   [sourceBrowser_ setDataSource:self];
   [sourceBrowser_ setCellsStyleMask:cellStyle];
   [sourceBrowser_ setCellSize:NSMakeSize(kThumbnailWidth, kThumbnailHeight)];
+  [sourceBrowser_ setAllowsMultipleSelection:NO];
 
   // Create a scroll view to host the image browser.
   NSRect imageBrowserScrollFrame = NSMakeRect(
       origin.x, origin.y, kPaddedWidth, 350);
   base::scoped_nsobject<NSScrollView> imageBrowserScroll(
       [[NSScrollView alloc] initWithFrame:imageBrowserScrollFrame]);
   [imageBrowserScroll setHasVerticalScroller:YES];
   [imageBrowserScroll setDocumentView:sourceBrowser_];
   [imageBrowserScroll setBorderType:NSBezelBorder];
   [imageBrowserScroll setAutoresizingMask:
@@ skipping 184 matching lines @@
 - (void)sourceThumbnailChangedAtIndex:(int)index {
   const DesktopMediaList::Source& source = media_list_->GetSource(index);
   NSImage* image = gfx::NSImageFromImageSkia(source.thumbnail);
 
   DesktopMediaPickerItem* item = [items_ objectAtIndex:index];
   [item setImageRepresentation:image];
   [sourceBrowser_ reloadData];
 }
 
 @end  // @interface DesktopMediaPickerController