[Mac] Retain location bar focus on switching to fullscreen and back.

chrome/browser/ui/cocoa/browser_window_controller_private.mm

Index: chrome/browser/ui/cocoa/browser_window_controller_private.mm
diff --git a/chrome/browser/ui/cocoa/browser_window_controller_private.mm b/chrome/browser/ui/cocoa/browser_window_controller_private.mm
index 4936bae19d9419395420a7237dccca59b4383d14..2f94f77149e1f2133bdbe48e49e1b2f0e7970ddb 100644
--- a/chrome/browser/ui/cocoa/browser_window_controller_private.mm
+++ b/chrome/browser/ui/cocoa/browser_window_controller_private.mm
@@ -1011,6 +1011,21 @@ willPositionSheet:(NSWindow*)sheet
     return;
   }
 
+  // Removing the location bar from the window causes it to resign first
+  // responder. Remember the location bar's focus state in order to restore
+  // it before returning.
+  BOOL locationBarHadFocus = [toolbarController_ locationBarHasFocus];
+  FullscreenToolbarVisibilityLockController* visibilityLockController = nil;
+  if (locationBarHadFocus) {
+    // The location bar, by being focused, has a visibility lock on the toolbar,
+    // and the location bar's removal from the view hierarchy will allow the
+    // toolbar to hide. Create a temporary visibility lock on the toolbar for
+    // the duration of the view hierarchy change.
+    visibilityLockController = [self fullscreenToolbarVisibilityLockController];
+    [visibilityLockController lockToolbarVisibilityForOwner:self
+                                              withAnimation:NO];
+  }
+
   // Remove all subviews that aren't the tabContentArea.
   for (NSView* view in [[[self.chromeContentView subviews] copy] autorelease]) {
     if (view != tabContentArea)
@@ -1033,6 +1048,14 @@ willPositionSheet:(NSWindow*)sheet
                             positioned:NSWindowAbove
                             relativeTo:nil];
   }
+
+  // Restore the location bar's focus state and remove the temporary visibility
+  // lock.
+  if (locationBarHadFocus) {
+    [self focusLocationBar:YES];
+    [visibilityLockController releaseToolbarVisibilityForOwner:self
+                                                 withAnimation:NO];
+  }
 }
 
 + (BOOL)systemSettingsRequireMavericksAppKitFullscreenHack {