Reduce browser work for multiple fetch plugins list requests...

Reduce browser work for consecutive fetch plugins list requests

I introduced a 3-second threshold value between consecutive fetch-plugin requests
that induce a disk read (on the file thread) by forcing a refresh. Now, if
multiple requests are made within the threshold values, no disk read will be
performed. Average request times have been reduced from 11ms/request down to
1ms/request.

BUG=44813
r=brettw


Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=57275

[brettw, 2010-08-24 20:18:39]

http://codereview.chromium.org/3192013/diff/22001/7003
File chrome/browser/renderer_host/resource_message_filter.h (right):

http://codereview.chromium.org/3192013/diff/22001/7003#newcode165
chrome/browser/renderer_host/resource_message_filter.h:165: base::TimeTicks
last_refresh_time_;  // Initialized to 0.
This should go down with the other data in this class (functions before data).
This name is also ambiguous. Can you call it the last_plugin_refresh_time_ or
something similar?

[ziadh, 2010-08-24 20:58:37]

http://codereview.chromium.org/3192013/diff/22001/7003
File chrome/browser/renderer_host/resource_message_filter.h (right):

http://codereview.chromium.org/3192013/diff/22001/7003#newcode165
chrome/browser/renderer_host/resource_message_filter.h:165: base::TimeTicks
last_refresh_time_;  // Initialized to 0.
On 2010/08/24 20:18:39, brettw wrote:
> This should go down with the other data in this class (functions before data).
> This name is also ambiguous. Can you call it the last_plugin_refresh_time_ or
> something similar?

Whoops, must have skipped over the #if defines, I didn't notice the other
functions ;D
Fixed, and renamed to last_plugin_refresh_time_.

[brettw, 2010-08-24 21:41:56]

LGTM with expanded comment.

http://codereview.chromium.org/3192013/diff/27001/28001
File chrome/browser/renderer_host/resource_message_filter.cc (right):

http://codereview.chromium.org/3192013/diff/27001/28001#newcode702
chrome/browser/renderer_host/resource_message_filter.cc:702: // this check is
performed before off-loading to the file thread.
Can you provide just a little more background here. I think it could use a
sentence about how pages request that the plugin list be refreshed (possibly
excessively often), plus a mention about how there could be multiple pages doing
this.

[ziadh, 2010-08-24 23:18:32]

http://codereview.chromium.org/3192013/diff/27001/28001
File chrome/browser/renderer_host/resource_message_filter.cc (right):

http://codereview.chromium.org/3192013/diff/27001/28001#newcode702
chrome/browser/renderer_host/resource_message_filter.cc:702: // this check is
performed before off-loading to the file thread.
On 2010/08/24 21:41:56, brettw wrote:
> Can you provide just a little more background here. I think it could use a
> sentence about how pages request that the plugin list be refreshed (possibly
> excessively often), plus a mention about how there could be multiple pages
doing
> this.

Done.