Make ScopedGetDC() CHECK fail if GetDC(NULL) returns NULL.

Use scoping objects more in the omnibox code.

BUG=110105
TEST=none
Review URL: https://chromiumcodereview.appspot.com/10545045

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@141087 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 17 insertions, 11 deletions

diff --git a/base/win/scoped_hdc.h b/base/win/scoped_hdc.h
index 9e2ea62..070c656 100644
--- a/base/win/scoped_hdc.h
+++ b/base/win/scoped_hdc.h
@@ -1,4 +1,4 @@
-// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Copyright (c) 2012 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.
 
@@ -21,8 +21,15 @@ class ScopedGetDC {
   explicit ScopedGetDC(HWND hwnd)
       : hwnd_(hwnd),
         hdc_(GetDC(hwnd)) {
-    DCHECK(!hwnd_ || IsWindow(hwnd_));
-    DCHECK(hdc_);
+    if (hwnd_) {
+      DCHECK(IsWindow(hwnd_));
+      DCHECK(hdc_);
+    } else {
+      // If GetDC(NULL) returns NULL, something really bad has happened, like
+      // GDI handle exhaustion.  In this case Chrome is going to behave badly no
+      // matter what, so we may as well just force a crash now.
+      CHECK(hdc_);
+    }
   }
 
   ~ScopedGetDC() {
diff --git a/chrome/browser/ui/views/omnibox/omnibox_view_win.cc b/chrome/browser/ui/views/omnibox/omnibox_view_win.cc
index 558f0ad..d27b578 100644
--- a/chrome/browser/ui/views/omnibox/omnibox_view_win.cc
+++ b/chrome/browser/ui/views/omnibox/omnibox_view_win.cc
@@ -20,6 +20,8 @@
 #include "base/string_util.h"
 #include "base/utf_string_conversions.h"
 #include "base/win/iat_patch_function.h"
+#include "base/win/scoped_hdc.h"
+#include "base/win/scoped_select_object.h"
 #include "base/win/windows_version.h"
 #include "chrome/app/chrome_command_ids.h"
 #include "chrome/browser/autocomplete/autocomplete_match.h"
@@ -482,10 +484,10 @@ OmniboxViewWin::OmniboxViewWin(AutocompleteEditController* controller,
               reinterpret_cast<LPARAM>(&WordBreakProc));
 
   // Get the metrics for the font.
-  HDC hdc = ::GetDC(NULL);
-  HGDIOBJ old_font = SelectObject(hdc, font_.GetNativeFont());
+  base::win::ScopedGetDC screen_dc(NULL);
+  base::win::ScopedSelectObject(screen_dc, font_.GetNativeFont());
   TEXTMETRIC tm = {0};
-  GetTextMetrics(hdc, &tm);
+  GetTextMetrics(screen_dc, &tm);
   int cap_height = font_.GetBaseline() - tm.tmInternalLeading;
   // The ratio of a font's x-height to its cap height.  Sadly, Windows
   // doesn't provide a true value for a font's x-height in its text
@@ -502,11 +504,8 @@ OmniboxViewWin::OmniboxViewWin(AutocompleteEditController* controller,
 
   // Get the number of twips per pixel, which we need below to offset our text
   // by the desired number of pixels.
-  const long kTwipsPerPixel = kTwipsPerInch / GetDeviceCaps(hdc, LOGPIXELSY);
-  // It's unsafe to delete a DC with a non-stock object selected, so restore the
-  // original font.
-  SelectObject(hdc, old_font);
-  ::ReleaseDC(NULL, hdc);
+  const long kTwipsPerPixel =
+      kTwipsPerInch / GetDeviceCaps(screen_dc, LOGPIXELSY);
 
   // Set the default character style -- adjust to our desired baseline.
   CHARFORMAT cf = {0};