Fix crash when allocation of very large HTML canvas fails.

skia/ext/platform_canvas.h

 // 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.
 
 #ifndef SKIA_EXT_PLATFORM_CANVAS_H_
 #define SKIA_EXT_PLATFORM_CANVAS_H_
 #pragma once
 
 // The platform-specific device will include the necessary platform headers
 // to get the surface type.
@@ skipping 91 matching lines @@
 //
 // Danger: the resulting device should not be saved. It will be invalidated
 // by the next call to save() or restore().
 SK_API SkDevice* GetTopDevice(const SkCanvas& canvas);
 
 // Creates a canvas with raster bitmap backing.
 // Set is_opaque if you are going to erase the bitmap and not use
 // transparency: this will enable some optimizations.
 SK_API SkCanvas* CreateBitmapCanvas(int width, int height, bool is_opaque);
 
+// Non-crashing version of CreateBitmapCanvas
+// returns NULL if allocation fails for any reason.
+// Use this instead of CreateBitmapCanvas in places that are likely to
+// attempt to allocate very large canvases (therefore likely to fail),
+// and where it is possible to recover gracefully from the failed allocation.
+SK_API SkCanvas* TryCreateBitmapCanvas(int width, int height, bool is_opaque);
+
 // Returns true if native platform routines can be used to draw on the
 // given canvas. If this function returns false, BeginPlatformPaint will
 // return NULL PlatformSurface.
 SK_API bool SupportsPlatformPaint(const SkCanvas* canvas);
 
 // Draws into the a native platform surface, |context|.  Forwards to
 // DrawToNativeContext on a PlatformDevice instance bound to the top device.
 // If no PlatformDevice instance is bound, is a no-operation.
 SK_API void DrawToNativeContext(SkCanvas* canvas, PlatformSurface context,
                                 int x, int y, const PlatformRect* src_rect);
@@ skipping 27 matching lines @@
   PlatformSurface platform_surface_;
 
   // Disallow copy and assign
   ScopedPlatformPaint(const ScopedPlatformPaint&);
   ScopedPlatformPaint& operator=(const ScopedPlatformPaint&);
 };
 
 }  // namespace skia
 
 #endif  // SKIA_EXT_PLATFORM_CANVAS_H_