External Registry loader should read from 32-bit HKLM registry hive

External Registry loader should read from 32-bit HKLM registry hive

To match behavior of 32-bit chrome on 64-bit Windows, the 64-bit version of
Chrome should read from the 32-bit hive.

BUG=408018
TEST=Follow reproduction steps in 408018.  Ensure extension remains when upgrading from 32-bit to 64-bit browser.

[Will Harris, 2014-09-16 18:43:31]

wfh@chromium.org changed reviewers:
+ miket@chromium.org

[miket_OOO, 2014-09-16 19:10:19]

On 2014/09/16 18:43:46, Will Harris wrote:

http://msdn.microsoft.com/en-us/library/windows/desktop/aa384129(v=vs.110).aspx
was helpful to understand the background.

Question: is this the right long-term solution? Should we be encouraging people
to write to the 64-bit hive, but meanwhile reading the 32-bit hive in addition
as a fallback? I don't quite understand enough about 64-bit Windows to be sure
my questions make sense, but it seems that with this CL, we've committed
everyone to writing to the 32-bit hive, even if they're fully 64-bit.

[Will Harris, 2014-09-16 20:12:10]

On 2014/09/16 19:10:19, miket wrote:
> On 2014/09/16 18:43:46, Will Harris wrote:
> 
>
http://msdn.microsoft.com/en-us/library/windows/desktop/aa384129(v=vs.110).aspx
> was helpful to understand the background.
> 
> Question: is this the right long-term solution? Should we be encouraging
people
> to write to the 64-bit hive, but meanwhile reading the 32-bit hive in addition
> as a fallback? I don't quite understand enough about 64-bit Windows to be sure
> my questions make sense, but it seems that with this CL, we've committed
> everyone to writing to the 32-bit hive, even if they're fully 64-bit.

Hi Mike, only the HKLM hive is redirected on WOW64 registry operations, so I
only added the KEY_WOW64_32KEY to the HKLM hive operation.  However if you think
it would be less confusing for readers of the code, I can add it to both
(the KEY_WOW64_32KEY flag has no effect on HKCU operations).

The behavior here of always reading from the 32-bit hive will mean that 64-bit
Chrome will have identical behavior to 32-bit Chrome running on 64-bit Windows
- i.e. they will both read from the Wow6432Node.  This is, I believe, the
behavior
we want.

grt@ did a load of similar reviews for me related to the installer, so I'll add
him here for comment.

[miket_OOO, 2014-09-16 20:32:08]

LGTM and thanks for the explanation!

[miket_OOO, 2014-09-16 20:38:52]

On 2014/09/16 20:32:08, miket wrote:
> LGTM and thanks for the explanation!

Per offline discussion, further patches are probably needed.

[Will Harris, 2014-10-07 20:53:52]

this will be fixed in https://codereview.chromium.org/616173003/ - closing.