Fix crash when allocation of very large HTML canvas fails.

Fix crash when allocation of very large HTML canvas fails.

This change introduces skia::TryCreateBitmapCanvas, which is a 
non-crashing version of CreateBitmapCanvas.  This patch alone
does not fix that crash. A patch in WebKit will be necessary
to make the ImageBuffer constructor in ImageBufferSkia.cpp
call TryCreateBitmapCanvas.

BUG=88038
TEST=http://www.atopon.org/maze/
Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=97474

[Justin Novosad, 2011-08-19 15:30:52]

PTAL

[alokp, 2011-08-19 15:34:39]

http://codereview.chromium.org/7686006/diff/3001/skia/ext/platform_canvas.cc
File skia/ext/platform_canvas.cc (right):

http://codereview.chromium.org/7686006/diff/3001/skia/ext/platform_canvas.cc#...
skia/ext/platform_canvas.cc:37: SkCanvas* TryCreateBitmapCanvas(int width, int
height, bool is_opaque) {
Couldn't you change the existing function to return NULL?

[junov1, 2011-08-19 15:50:25]

http://codereview.chromium.org/7686006/diff/3001/skia/ext/platform_canvas.cc
File skia/ext/platform_canvas.cc (right):

http://codereview.chromium.org/7686006/diff/3001/skia/ext/platform_canvas.cc#...
skia/ext/platform_canvas.cc:37: SkCanvas* TryCreateBitmapCanvas(int width, int
height, bool is_opaque) {
On 2011/08/19 15:34:39, Alok Priyadarshi wrote:
> Couldn't you change the existing function to return NULL?

There are many places that currently call CreateBitmapCanvas and require it to
succeed (no graceful failure path).  The way in which CreateBitmapCanvas crashes
is actually very useful because it provides some diagnostics (see
CrashForBitmapAllocationFailure in platform_canvas_win.cc).

[alokp, 2011-08-19 15:57:19]

I see. LGTM.