Generalize ImageForContainer

Generalize ImageForContainer

Following https://codereview.chromium.org/25105004/, I've added the infrastructure that enables adding image data that will not be shared among different representations of that image within the same renderer to Bitmap images.
A candidate for such image data would be the intrinsic size factor as part of the srcset implementation.

BUG=299556

[Yoav Weiss, 2013-10-04 14:07:45]

As discussed in https://codereview.chromium.org/25105004/, I've chosen option #1
to generalize the ImageForContainer mechanism to Bitmap images.

I've made this a separate CL for clarity.

[pdr., 2013-10-04 21:08:04]

Other than some minor nits, I think this looks great.

I would like one more person on this review so I've added Eric Seidel. @eseidel,
yoav needs to store per-renderer information about an image for implementing
srcset and he's going about it by generalizing the SVGImageForContainer design.
This patch just generalizes it, and a followup will actually put the bits onto
ImageForContainer. Can you comment on this high-level design? For reference,
here's a short writeup about how it works:
https://docs.google.com/a/chromium.org/document/d/1J3MPhE2nSQz_HQ0Ext6ZIlnMzV...

https://codereview.chromium.org/25627006/diff/1/Source/core/core.gypi
File Source/core/core.gypi (right):

https://codereview.chromium.org/25627006/diff/1/Source/core/core.gypi#newcode...
Source/core/core.gypi:2837: 'platform/graphics/ImageCache.cpp',
Nit: Not your fault, but while we're here can you rename ImageCache to
ImageSizeCache (or similar, as you see fit)?

https://codereview.chromium.org/25627006/diff/1/Source/core/platform/graphics...
File Source/core/platform/graphics/ImageForContainer.cpp (right):

https://codereview.chromium.org/25627006/diff/1/Source/core/platform/graphics...
Source/core/platform/graphics/ImageForContainer.cpp:34: return m_image->size();
Is this necessary? I thought we'd go through the lines below this.

[Yoav Weiss, 2013-10-08 08:47:23]

https://codereview.chromium.org/25627006/diff/1/Source/core/platform/graphics...
File Source/core/platform/graphics/ImageForContainer.cpp (right):

https://codereview.chromium.org/25627006/diff/1/Source/core/platform/graphics...
Source/core/platform/graphics/ImageForContainer.cpp:34: return m_image->size();
On 2013/10/04 21:08:04, pdr wrote:
> Is this necessary? I thought we'd go through the lines below this.

m_containerSize and m_zoom are not defined for non-SVG images, so this is how I
handled it. I could also defined them for bitmap images, if that's preferable.

[Yoav Weiss, 2013-10-11 07:54:50]

Since we eventually took a different architecture for image data storage, I'm
closing this CL.