Alert points to: Remove unnecessary gin dependency from content/browser/
https://codereview.chromium.org/2795263003 (1397ae312f38f559bea425268f79b3427b00b7da)

However, the commit does not but *remove* a dependency, so it's quite odd to see a jump here. I'll investigate further.

Crazily, this actually was the offender. Size diff:

13 symbols added (+), 48 changed (~), 13 removed (-), 316860 unchanged (not shown)
Showing 74 symbols with total size: 56560 bytes
.text=55.2kb     .rodata=0 bytes    other=0 bytes    total=55.2kb
First columns are: running total, type, size
~    56560 t@0x0         56560   {no path}
               ** aggregate padding of diff'ed symbols
~    54572 r@0x29ee064   -1988   third_party/WebKit/Source/platform/graphics/compositing/PaintChunksToCcLayer.cpp
~    56548 r@0x29f6ba8   1976    v8/src/json-stringifier.cc
~    54976 d@0x2dd0008   -1572   third_party/WebKit/Source/platform/graphics/GraphicsTypes.cpp
~    56548 d@0x2dd0270   1572    v8/src/bootstrapper.cc
~    56332 r@0x29ef6b0   -216    third_party/WebKit/Source/platform/transforms/AffineTransform.cpp
~    56532 r@0x2a03b10   200     v8/src/arm/interface-descriptors-arm.cc
~    56616 r@0x29edf90   84      third_party/WebKit/Source/platform/graphics/OffscreenCanvasFrameDispatcherImpl.cpp
~    56684 r@0x2a1768c   68      v8/src/interpreter/interpreter-intrinsics-generator.cc
~    56620 r@0x29eda08   -64     media/blink/webmediaplayer_impl.cc
~    56680 r@0x29ee0a4   60      third_party/WebKit/Source/platform/graphics/compositing/PropertyTreeManager.cpp
~    56740 r@0x29f398c   60      v8/src/code-stub-assembler.cc
~    56684 r@0x2a17604   -56     v8/src/builtins/builtins-string-gen.cc
~    56734 r@0x2a17630   50      v8/src/ic/accessor-assembler.cc
~    56784 r@0x2a17ad8   50      third_party/WebKit/Source/web/LinkHighlightImpl.cpp
~    56832 r@0x29edc00   48      cc/blink/web_layer_impl_fixed_bounds.cc
~    56784 r@0x2a151c0   -48     v8/src/inspector/v8-debugger-script.cc
~    56738 r@0x2a17c10   -46     third_party/WebKit/Source/web/WebFrameContentDumper.cpp
~    56694 r@0x29f3a04   -44     v8/src/compiler/c-linkage.cc
~    56650 r@0x2a17c14   -44     third_party/WebKit/Source/web/WebInputEventConversion.cpp
~    56610 r@0x29ed898   -40     media/blink/video_frame_compositor.cc
~    56650 r@0x29f3360   40      v8/src/bignum.cc
~    56610 r@0x2a175ec   -40     v8/src/builtins/builtins-sharedarraybuffer-gen.cc
~    56638 r@0x29eca50   28      third_party/WebKit/Source/platform/wtf/dtoa/bignum.cc
~    56610 r@0x29f6b78   -28     v8/src/interpreter/interpreter.cc
~    56582 r@0x29f73ac   -28     v8/src/log.cc
~    56554 r@0x0         -28     {no path}
               ** aggregate padding of diff'ed symbols
~    56582 r@0x260fc48   28      {no path}
               ** merge strings
~    56558 r@0x2a03a44   -24     v8/src/arm/code-stubs-arm.cc
~    56582 r@0x2a1760c   24      v8/src/builtins/builtins-typedarray-gen.cc
~    56606 r@0x2a1766c   24      v8/src/interpreter/interpreter-generator.cc
~    56584 r@0x29ee850   -22     third_party/WebKit/Source/platform/image-decoders/ImageDecoder.cpp
~    56564 r@0x29f32d8   -20     v8/src/asmjs/asm-typer.cc
~    56544 r@0x29f32ec   -20     v8/src/asmjs/asm-wasm-builder.cc
+    56564 t@0x13dab9c   20      third_party/WebKit/Source/web/InspectorOverlay.cpp
               blink::ScriptWrappable::mainWorldWrapper const
-    56544 t@0xdcc810    -20     gin/function_template.cc
<snip>



Symbol gaps before:
>>> Print(symbols1.WhereNameMatches(r'\*\* sym'))
Showing 8 symbols with total size: 222558 bytes
.text=217kb      .rodata=0 bytes    other=0 bytes    total=217kb
First columns are: running total, type, size
   91122 t@0x229e750   91122   components/subresource_filter/core/common/indexed_ruleset.cc
             ** symbol gap 7
  139892 t@0x1a968e0   48770   third_party/webrtc/modules/bitrate_controller/send_side_bandwidth_estimation.cc
             ** symbol gap 5
  179546 t@0x1e94390   39654   third_party/WebKit/Source/core/html/forms/RadioButtonGroupScope.cpp
             ** symbol gap 6
  213588 t@0x1696d30   34042   media/base/audio_decoder_config.cc
             ** symbol gap 4
  219810 t@0x6be23c    6222    third_party/icu/source/common/uenum.c
             ** symbol gap 0
  221042 t@0xab26c4    1232    content/browser/appcache/appcache_database.cc
             ** symbol gap 1
  221942 t@0x129aa40   900     v8/src/builtins/builtins-regexp-gen.cc
             ** symbol gap 3
  222558 t@0xea6920    616     v8/src/compiler/ast-loop-assignment-analyzer.cc
             ** symbol gap 2


Symbol gaps after:
>>> Print(symbols2.WhereNameMatches(r'\*\* sym'))
Showing 8 symbols with total size: 279160 bytes
.text=272kb      .rodata=0 bytes    other=0 bytes    total=272kb
First columns are: running total, type, size
  144324 t@0x22aca30   144324  components/subresource_filter/core/common/indexed_ruleset.cc
             ** symbol gap 7
  193082 t@0x1a96094   48758   third_party/webrtc/modules/bitrate_controller/send_side_bandwidth_estimation.cc
             ** symbol gap 5
  239694 t@0x1e9567c   46612   third_party/WebKit/Source/core/html/forms/RadioInputType.cpp
             ** symbol gap 6
  270682 t@0x1696284   30988   media/base/audio_discard_helper.cc
             ** symbol gap 4
  276560 t@0x6be0e4    5878    third_party/icu/source/common/uenum.c
             ** symbol gap 0
  277792 t@0xab2544    1232    content/browser/appcache/appcache_database.cc
             ** symbol gap 1
  278516 t@0xea67dc    724     third_party/WebKit/Source/platform/scroll/ScrollableArea.cpp
             ** symbol gap 2
  279160 t@0x129aa60   644     v8/src/runtime/runtime.cc
             ** symbol gap 3


I think the only action here is to learn more about why these gaps exist.

 Issue 789979  has been merged into this issue.

Fairly sure these are range extension thunks. They don't seem to exist with use_lld=true (or are labelled as something). Closing.