Fix bug where we were not displaying icons in the management

Fix bug where we were not displaying icons in the management
UI for disabled extensions.

Also, desaturate the icons of disabled extensions to make them
look more disabledy.

BUG=25963
TEST=On the extensions page, disable an extension, then press
reload. You should see a greyscale version of the icon.

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=31139

[Aaron Boodman, 2009-11-05 00:54:56]

screen caps coming as soon as i sync and merge with your work.

[Aaron Boodman, 2009-11-05 01:32:02]

Screen cap here:
http://dl.getdropbox.com/u/124107/disabledness.png

[Finnur, 2009-11-05 03:55:08]

Awesome. LGTM, with just nits.

http://codereview.chromium.org/360039/diff/1001/1003
File chrome/browser/extensions/extensions_ui.h (right):

http://codereview.chromium.org/360039/diff/1001/1003#newcode69
Line 69: //    look more disabled.
nit: disabled/enabled is a binary state. Drop the word 'more'. :)

http://codereview.chromium.org/360039/diff/1001/1003#newcode72
Line 72: IconLoader(ExtensionsDOMHandler* handler);
missing explicit keyword?

http://codereview.chromium.org/360039/diff/1001/1003#newcode175
Line 175: // good icon exists.
nit: You don't exactly return NULL here... :)

http://codereview.chromium.org/360039/diff/1001/1003#newcode185
Line 185: // Takes ownership of |json_data|.
nit: maybe: Takes ownership of |json_data| and notifies the HTML about it.
?

http://codereview.chromium.org/360039/diff/1001/1004
File chrome/browser/resources/extensions_ui.html (right):

http://codereview.chromium.org/360039/diff/1001/1004#newcode630
Line 630: width="48" height="48" />
nit: Doesn't this fit in one line (maybe two)?

http://codereview.chromium.org/360039/diff/9/11
File chrome/browser/extensions/extensions_ui.cc (left):

http://codereview.chromium.org/360039/diff/9/11#oldcode35
Line 35: 
nit: Did you delete this line on purpose?
I think I've seen people put the resources at the bottom in a separate section.
If we are going to have this in one section, shouldn't this be before net/* to
maintain alphabetical sorting? If we are going to have two sections, then the
webkit include moves up.

http://codereview.chromium.org/360039/diff/9/11
File chrome/browser/extensions/extensions_ui.cc (right):

http://codereview.chromium.org/360039/diff/9/11#newcode128
Line 128:
///////////////////////////////////////////////////////////////////////////////
nit: Add one more / to complete 80 columns. :)

http://codereview.chromium.org/360039/diff/9/11#newcode172
Line 172: CHECK(extension->GetBoolean(L"enabled", &enabled));
nit: Why CHECK here instead of DCHECK?

http://codereview.chromium.org/360039/diff/9/12
File chrome/browser/extensions/extensions_ui.h (right):

http://codereview.chromium.org/360039/diff/9/12#newcode198
Line 198: // Used to load icons.
nit: This comment is a bit scarce. Can you add: "asynchronously on the File
thread"?