DevTools window doesn't restore its minimal size if it's shrinked to zero.

chrome/browser/ui/cocoa/dev_tools_controller.mm

 // Copyright (c) 2011 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/dev_tools_controller.h"
 
 #include <algorithm>
 
 #include <Cocoa/Cocoa.h>
 
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/debugger/devtools_window.h"
 #include "chrome/browser/prefs/pref_service.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/ui/tab_contents/tab_contents_wrapper.h"
 #import "chrome/browser/ui/cocoa/view_id_util.h"
 #include "chrome/common/pref_names.h"
 #include "content/browser/tab_contents/tab_contents.h"
 
 namespace {
 
-// Default offset of the contents splitter in pixels.
-const int kDefaultContentsSplitOffset = 400;
-
-// Never make the web part of the tab contents smaller than this (needed if the
-// window is only a few pixels high).
-const int kMinWebHeight = 50;
+// Minimal height of devtools pane or content pane when devtools are docked
+// to the browser window.
+const int kMinDevToolsHeight = 50;
+const int kMinContentsHeight = 50;
 
 }  // end namespace
 
 
 @interface DevToolsController (Private)
 - (void)showDevToolsContents:(TabContents*)devToolsContents
                  withProfile:(Profile*)profile;
 - (void)resizeDevToolsToNewHeight:(CGFloat)height;
 @end
 
@@ skipping 55 matching lines @@
     // set to VIEW_ID_TAB_CONTAINER initially, so we need to change it to
     // VIEW_ID_DEV_TOOLS_DOCKED here.
     view_id_util::SetID(
         devToolsContents->GetNativeView(), VIEW_ID_DEV_TOOLS_DOCKED);
 
     CGFloat splitOffset = 0;
     if ([subviews count] == 1) {
       // Load the default split offset.
       splitOffset = profile->GetPrefs()->
           GetInteger(prefs::kDevToolsSplitLocation);
-      if (splitOffset < 0) {
-        // Initial load, set to default value.
-        splitOffset = kDefaultContentsSplitOffset;
-      }
+      if (splitOffset < 0)
+        splitOffset = NSHeight([[subviews objectAtIndex:0] frame]) * 2 / 3;
+
       [splitView_ addSubview:[contentsController_ view]];
     } else {
       DCHECK_EQ([subviews count], 2u);
       // If devtools are already visible, keep the current size.
       splitOffset = NSHeight([[subviews objectAtIndex:1] frame]);
     }
 
     // Make sure |splitOffset| isn't too large or too small.
-    splitOffset = std::max(static_cast<CGFloat>(kMinWebHeight), splitOffset);
-    splitOffset =
-        std::min(splitOffset, NSHeight([splitView_ frame]) - kMinWebHeight);
+    splitOffset = std::min(NSHeight([splitView_ frame]) - kMinDevToolsHeight,
+                           splitOffset);
+    splitOffset = std::max(static_cast<CGFloat>(kMinContentsHeight),
+                           splitOffset);
+    if (splitOffset < 0)
+      splitOffset = NSHeight([[subviews objectAtIndex:0] frame]) * 2 / 3;
     DCHECK_GE(splitOffset, 0) << "kMinWebHeight needs to be smaller than "
                               << "smallest available tab contents space.";
 
     [self resizeDevToolsToNewHeight:splitOffset];
   } else {
     if ([subviews count] > 1) {
       NSView* oldDevToolsContentsView = [subviews objectAtIndex:1];
       // Store split offset when hiding devtools window only.
       int splitOffset = NSHeight([oldDevToolsContentsView frame]);
 
@@ skipping 34 matching lines @@
   // Return NO for the devTools view to indicate that it should not be resized
   // automatically. It preserves the height set by the user and also keeps
   // view height the same while changing tabs when one of the tabs shows infobar
   // and others are not.
   if ([[splitView_ subviews] indexOfObject:subview] == 1)
     return NO;
   return YES;
 }
 
 @end