use log2(scale) to compute mip level

use log2(scale) to compute mip level

BUG=skia:

Committed: https://skia.googlesource.com/skia/+/15fd47f8a07615a7f5d78581aee4c80ff9f17fd9

[reed1, 2015-01-15 22:26:57]

reed@google.com changed reviewers:
+ jvanverth@google.com, robertphillips@google.com

[reed1, 2015-01-15 22:27:04]

The CQ bit was checked by reed@google.com

[reed1, 2015-01-15 22:27:08]

The CQ bit was unchecked by reed@google.com

[reed1, 2015-01-15 22:28:05]

won't land until this lands first

https://codereview.chromium.org/857463002/

[robertphillips, 2015-01-16 01:13:38]

lgtm

https://codereview.chromium.org/849333002/diff/40001/include/core/SkFloatingP...
File include/core/SkFloatingPoint.h (right):

https://codereview.chromium.org/849333002/diff/40001/include/core/SkFloatingP...
include/core/SkFloatingPoint.h:91: #define sk_float_log(x)         logf(x)
Map sk_float_log2 to log2f here?

[reed1, 2015-01-16 13:00:11]

https://codereview.chromium.org/849333002/diff/40001/include/core/SkFloatingP...
File include/core/SkFloatingPoint.h (right):

https://codereview.chromium.org/849333002/diff/40001/include/core/SkFloatingP...
include/core/SkFloatingPoint.h:91: #define sk_float_log(x)         logf(x)
On 2015/01/16 01:13:37, robertphillips wrote:
> Map sk_float_log2 to log2f here?

Done.

[reed1, 2015-01-16 13:00:34]

The CQ bit was checked by reed@google.com

[commit-bot: I haz the power, 2015-01-16 13:01:41]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/849333002/60001

[commit-bot: I haz the power, 2015-01-16 13:04:21]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-01-16 13:04:22]

Try jobs failed on following builders:
  Build-Ubuntu13.10-GCC4.8-Arm7-Debug-Android-Trybot on client.skia.compile
(http://build.chromium.org/p/client.skia.compile/builders/Build-Ubuntu13.10-GC...)

[reed1, 2015-01-16 14:24:34]

The CQ bit was checked by reed@google.com

[commit-bot: I haz the power, 2015-01-16 14:24:52]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/849333002/80001

[commit-bot: I haz the power, 2015-01-16 14:26:13]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-01-16 14:26:14]

Try jobs failed on following builders:
  Build-Ubuntu13.10-GCC4.8-Arm7-Debug-Android-Trybot on client.skia.compile
(http://build.chromium.org/p/client.skia.compile/builders/Build-Ubuntu13.10-GC...)

[reed1, 2015-01-16 14:41:34]

The CQ bit was checked by reed@google.com

[commit-bot: I haz the power, 2015-01-16 14:42:12]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/849333002/100001

[commit-bot: I haz the power, 2015-01-16 14:42:14]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-01-16 14:42:15]

Failed to apply patch for expectations/gm/ignored-tests.txt:
While running git apply --index -3 -p1;
  error: patch failed: expectations/gm/ignored-tests.txt:33
  Falling back to three-way merge...
  Applied patch to 'expectations/gm/ignored-tests.txt' with conflicts.
  U expectations/gm/ignored-tests.txt

Patch:       expectations/gm/ignored-tests.txt
Index: expectations/gm/ignored-tests.txt
diff --git a/expectations/gm/ignored-tests.txt
b/expectations/gm/ignored-tests.txt
index
9469b2c4e60263b5ac2155aae2f002f91de98945..b870f1c46260edf2bac1359c0f0f6aa842667844
100644
--- a/expectations/gm/ignored-tests.txt
+++ b/expectations/gm/ignored-tests.txt
@@ -33,6 +33,17 @@
 ## epoger will rebaseline by 25 Dec 2013
 #gradtext
 
+# reed - rebase after mipmap level improvement
+downsamplebitmap_image_medium_mandrill_512
+downsamplebitmap_image_medium_mandrill_132x132_12x12
+downsamplebitmap_image_medium_mandrill_512.png
+downsamplebitmap_image_medium_mandrill_132x132_12x12.astc
+downsamplebitmap_checkerboard_medium_512_256
+downsamplebitmap_text_medium_72.00pt
+filterindiabox
+coloremoji
+fontmgr_iter
+
 # robertphillips - skia:2995
 blurrects

[reed1, 2015-01-16 15:07:41]

The CQ bit was checked by reed@google.com

[commit-bot: I haz the power, 2015-01-16 15:08:34]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/849333002/120001

[commit-bot: I haz the power, 2015-01-16 15:18:14]

Committed patchset #7 (id:120001) as
https://skia.googlesource.com/skia/+/15fd47f8a07615a7f5d78581aee4c80ff9f17fd9

[reed1, 2015-01-16 15:26:41]

A revert of this CL (patchset #7 id:120001) has been created in
https://codereview.chromium.org/856783004/ by reed@google.com.

The reason for reverting is: need more suppressions.