All graphs for this bug:
  https://chromeperf.appspot.com/group_report?bug_id=631421

Original alerts at time of bug-filing:
  https://chromeperf.appspot.com/group_report?keys=agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgICg-vjNqgkM


Bot(s) for this bug's original alert(s):

android-one

Started bisect job https://chromeperf.appspot.com/buildbucket_job_status/9006080449122571488

Hmm Bruce, your https://codereview.chromium.org/2172033002 seems the only possible candidate in the list.
Which is weird, the only side effect I can see there is switching gpu and few other targets from source_set to static_libraries. Any idea on how could that affect the performance of an Android official build (which is a static_build).
Let's wait for bisect to confirm, I'd not expect static_library vs source_set to make a perf difference in non-component builds. hmm

===== BISECT JOB RESULTS =====
Status: completed


===== SUSPECTED CL(s) =====
Subject : Reland of Shrink gn's chrome.dll - now smaller than gyp's (patchset #1 id:1 of https://codereview.chromium.org/2173453004/ )
Author  : brucedawson
Commit description:
  
Reason for revert (reland):
Problem is understood, mostly. Needed to slightly update the patch to fix it. Blink split counts were copied from gyp.

Original issue's description (with indents removed):
More work to shrink gn's chrome.dll

The three largest globals that were present in gn's chrome.dll but not in gyp's chrome.dll were eliminated by using /verbose linker output to track the object files that pulled them in and then conditionally changing source_set targets to static_library targets. Specifically:

unigram_table, in compact_enc_det.obj
- Referenced by TextResourceDecoder.obj from //third_party/WebKit/Source/core:html - some other source_set targets in this file were also modified

gpu::ApplyFramebufferAttachmentCMAAINTELResourceManager::cmaa_frag_s1_ and cmaa_frag_s2_, in gles2_cmd_apply_framebuffer_attachment_cmaa_intel.obj from //gpu/command_buffer/service:service_sources
- Referenced by gpu_command_buffer_stub.obj from //gpu/ipc/service:ipc_service_sources
- Referenced by gpu_video_decode_accelerator.obj from //media/gpu/ipc/service:service
- Referenced by gpu_child_thread.obj from //content/gpu:gpu_sources
- Referenced by gpu_video_decode_accelerator_factory.obj from //content/public/gpu:gpu_sources

As of R406709 this shrinks gn's 32-bit official chrome.dll file size from 38,907,904 bytes to 37,571,584 bytes - an unexpected 1,336,320 byte savings, mostly from the .text section. There is also ~67,000 bytes of memory-only savings in the zero-init part of the .data section.

At the same revision gyp's 32-bit official chrome.dll file size is 37,843,456 bytes - 271,872 bytes *larger* than the gn version.

There are still globals that are present in gn's chrome.dll but not gyp's chrome.dll, so the optimization technique can still be applied some more, but the priority is much lower now that gn is winning.

This is a follow-on to crrev.com/2163823002.

TBR=brettw@chromium.org,achuith@chromium.org
BUG= 624274 
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_optional_gpu_tests_rel;master.tryserver.chromium.mac:mac_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel

Review-Url: https://codereview.chromium.org/2172033002
Cr-Commit-Position: refs/heads/master@{#407372}
Commit  : 6e53a2e16dc26dec41494b02da83a1221b72e7c4
Date    : Sat Jul 23 19:37:25 2016


===== TESTED REVISIONS =====
Revision         Mean     Std Dev  N  Good?
chromium@407366  1396.57  16.1142  5  good
chromium@407369  1411.69  24.3878  5  good
chromium@407371  1394.38  11.5966  5  good
chromium@407372  1646.69  26.7102  5  bad    <--

Bisect job ran on: android_one_perf_bisect
Bug ID: 631421

Test Command: src/tools/perf/run_benchmark -v --browser=android-chromium --output-format=chartjson --upload-results --also-run-disabled-tests blink_perf.dom
Test Metric: modify-element-title/modify-element-title
Relative Change: 17.91%
Score: 99.9

Buildbot stdio: http://build.chromium.org/p/tryserver.chromium.perf/builders/android_one_perf_bisect/builds/1438
Job details: https://chromeperf.appspot.com/buildbucket_job_status/9006080449122571488


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