Fix transparent crack at top of page while resizing devtools NSSplitView divider.

chrome/browser/ui/cocoa/dev_tools_controller.mm

Index: chrome/browser/ui/cocoa/dev_tools_controller.mm
diff --git a/chrome/browser/ui/cocoa/dev_tools_controller.mm b/chrome/browser/ui/cocoa/dev_tools_controller.mm
index ad9c3f9988688f1b72eb9806f844557c1918e633..349a6cabf61967ecbc5107fa1eed38b28d2025de 100644
--- a/chrome/browser/ui/cocoa/dev_tools_controller.mm
+++ b/chrome/browser/ui/cocoa/dev_tools_controller.mm
@@ -30,6 +30,18 @@ const int kMinContentsSize = 50;
 }  // end namespace
 
 
+@interface GraySplitView : NSSplitView
+- (NSColor*)dividerColor;
+@end
+
+
+@implementation GraySplitView
+- (NSColor*)dividerColor {
+  return [NSColor darkGrayColor];
+}
+@end
+
+
 @interface DevToolsController (Private)
 - (void)showDevToolsContents:(WebContents*)devToolsContents
                  withProfile:(Profile*)profile;
@@ -43,16 +55,22 @@ const int kMinContentsSize = 50;
 
 - (id)init {
   if ((self = [super init])) {
-    splitView_.reset([[NSSplitView alloc] initWithFrame:NSZeroRect]);
+    splitView_.reset([[GraySplitView alloc] initWithFrame:NSZeroRect]);
     [splitView_ setDividerStyle:NSSplitViewDividerStyleThin];
     [splitView_ setVertical:NO];
     [splitView_ setAutoresizingMask:NSViewWidthSizable|NSViewHeightSizable];
+    [splitView_ setDelegate:self];
 
     dockToRight_ = NO;
   }
   return self;
 }
 
+- (void)dealloc {
+  [splitView_ setDelegate:nil];
+  [super dealloc];
+}
+
 - (NSView*)view {
   return splitView_.get();
 }
@@ -210,4 +228,8 @@ const int kMinContentsSize = 50;
   return YES;
 }
 
+-(void)splitViewWillResizeSubviews:(NSNotification *)notification {
+  [[splitView_ window] disableScreenUpdatesUntilFlush];
+}
+
 @end