Add sanity check to troubleshoot crbug.com/374273

chrome/browser/ui/views/frame/opaque_browser_frame_view.cc

 // 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.
 
 #include "chrome/browser/ui/views/frame/opaque_browser_frame_view.h"
 
 #include <algorithm>
 #include <string>
 
 #include "base/compiler_specific.h"
@@ skipping 738 matching lines @@
 
   gfx::Rect client_area_bounds =
       layout_->CalculateClientAreaBounds(width(), height());
   SkColor toolbar_color = tp->GetColor(ThemeProperties::COLOR_TOOLBAR);
 
   if (browser_view()->IsToolbarVisible()) {
     // The client edge images always start below the toolbar corner images.  The
     // client edge filled rects start there or at the bottom of the toolbar,
     // whichever is shorter.
     gfx::Rect toolbar_bounds(browser_view()->GetToolbarBounds());
-    image_top += toolbar_bounds.y() +
-        tp->GetImageSkiaNamed(IDR_CONTENT_TOP_LEFT_CORNER)->height();
+
+    gfx::ImageSkia* content_top_left_corner =
+        tp->GetImageSkiaNamed(IDR_CONTENT_TOP_LEFT_CORNER);
+    // TODO(oshima): Sanity checks for crbug.com/374273. Remove when it's fixed.
+    CHECK(content_top_left_corner);
+    CHECK(!content_top_left_corner->isNull());
+
+    image_top += toolbar_bounds.y() + content_top_left_corner->height();
     client_area_top = std::min(image_top,
         client_area_top + toolbar_bounds.bottom() - kClientEdgeThickness);
   } else if (!browser_view()->IsTabStripVisible()) {
     // The toolbar isn't going to draw a client edge for us, so draw one
     // ourselves.
     gfx::ImageSkia* top_left = tp->GetImageSkiaNamed(IDR_APP_TOP_LEFT);
     gfx::ImageSkia* top_center = tp->GetImageSkiaNamed(IDR_APP_TOP_CENTER);
     gfx::ImageSkia* top_right = tp->GetImageSkiaNamed(IDR_APP_TOP_RIGHT);
     int top_edge_y = client_area_top - top_center->height();
     int height = client_area_top - top_edge_y;
@@ skipping 125 matching lines @@
 
 int OpaqueBrowserFrameView::GetTopAreaHeight() const {
   gfx::ImageSkia* frame_image = GetFrameImage();
   int top_area_height = frame_image->height();
   if (browser_view()->IsTabStripVisible()) {
     top_area_height = std::max(top_area_height,
       GetBoundsForTabStrip(browser_view()->tabstrip()).bottom());
   }
   return top_area_height;
 }