Create a star symbol for gaps at the start & end of sections

tools/binary_size/libsupersize/testdata/FullDescription.golden

Index: tools/binary_size/libsupersize/testdata/FullDescription.golden
diff --git a/tools/binary_size/libsupersize/testdata/FullDescription.golden b/tools/binary_size/libsupersize/testdata/FullDescription.golden
index 9772dad886d2e119abd5adcd5db4562ec2729cee..86973eef6b7161a2661b8b62ce47555320817697 100644
--- a/tools/binary_size/libsupersize/testdata/FullDescription.golden
+++ b/tools/binary_size/libsupersize/testdata/FullDescription.golden
@@ -39,33 +39,50 @@ Other section sizes:
     .strtab: 34,841,854 bytes
     .symtab: 17,166,112 bytes
 
-Section r: has 44.6% of 2641540 bytes accounted for from 6 symbols. 3286112 bytes are unaccounted for.
-* Padding accounts for 366 bytes (0.0%)
-* Contains 0 aliases
+Section r: has 100.0% of 5927652 bytes accounted for from 7 symbols. 0 bytes are unaccounted for.
+* Padding accounts for 11 bytes (0.0%)
+* 2 placeholders (symbols that start with **) account for 5927509.0 bytes (100.0%)
 * 0 symbols have shared ownership
-* Without 1 merge sections (accounting for 2641394 bytes):
-  * Section r: has 0.0% of 146 bytes accounted for from 5 symbols. 5927506 bytes are unaccounted for.
 Section b: has 40.3% of 524520 bytes accounted for from 6 symbols. 775936 bytes are unaccounted for.
 * Padding accounts for 196 bytes (0.0%)
-* Contains 0 aliases
 * 0 symbols have shared ownership
-Section d: has 40.4% of 790284 bytes accounted for from 13 symbols. 1166732 bytes are unaccounted for.
+Section d: has 100.0% of 1957016 bytes accounted for from 15 symbols. 0 bytes are unaccounted for.
 * Padding accounts for 16 bytes (0.0%)
-* Contains 0 aliases
+* 2 placeholders (symbols that start with **) account for 1166732.0 bytes (59.6%)
 * 0 symbols have shared ownership
-Section t: has 0.2% of 79710 bytes accounted for from 16 symbols. 35821002 bytes are unaccounted for.
-* Padding accounts for 9806 bytes (12.3%)
-* Contains 5 aliases, mapped to 2 addresses (60 bytes)
+Section t: has 100.0% of 35900712 bytes accounted for from 16 symbols. 0 bytes are unaccounted for.
+* Padding accounts for 48 bytes (0.0%)
+* 1 placeholders (symbols that start with **) account for 35830760.0 bytes (99.8%)
+* Contains 5 aliases, mapped to 2 unique addresses (60 bytes)
 * 1 symbols have shared ownership (12 bytes)
-* Without 1 merge sections (accounting for 9758 bytes):
-  * Section t: has 0.2% of 69952 bytes accounted for from 15 symbols. 35830760 bytes are unaccounted for.
 
-Showing 41 symbols with total pss: 4036054 bytes
-.text=77.8kb     .rodata=2.52mb     other=1.25mb     total=3.85mb
+Showing 44 symbols with total pss: 44309900 bytes
+.text=34.2mb     .rodata=5.65mb     other=2.37mb     total=42.3mb
 Number of object files: 10
 
 First columns are: running total, address, pss
- 2641394 r@Group      pss=2641394  padding=352  size_without_padding=2641042  count=2
+35830760 t@Group      pss=35830760  padding=35830760  size_without_padding=0  count=3
+             source_path= 	object_path=
+             flags={}  name=** symbol gaps
+> 35821002 t@0x24ca628  pss=35821002  padding=35821002  size_without_padding=0
+               source_path= 	object_path=
+               flags={}  name=** symbol gap 2 (end of section)
+> 35826720 t@0x28f000   pss=5718  padding=5718  size_without_padding=0
+               source_path=third_party/icu/ucnv_ext.c 	object_path=third_party/icu/icuuc/ucnv_ext.o
+               flags={}  name=** symbol gap 0
+> 35830760 t@0x2a1000   pss=4040  padding=4040  size_without_padding=0
+               source_path=third_party/container.c 	object_path=third_party/WebKit.a/ContiguousContainer.o
+               flags={}  name=** symbol gap 1
+39116875 r@Group      pss=3286115  padding=3286115  size_without_padding=0  count=2
+             source_path= 	object_path=
+             flags={}  name=** symbol gaps
+>  3286112 r@0x2c158e4  pss=3286112  padding=3286112  size_without_padding=0
+               source_path= 	object_path=
+               flags={}  name=** symbol gap 3 (end of section)
+>  3286115 r@0x284e364  pss=3  padding=3  size_without_padding=0
+               source_path=base/page_allocator.cc 	object_path=base/base/page_allocator.o
+               flags={}  name=** symbol gap 2
+41758269 r@Group      pss=2641394  padding=352  size_without_padding=2641042  count=2
              source_path= 	object_path=
              flags={}  name=** merge strings
 >  1965409 r@0x266e600  pss=1965409  padding=0  size_without_padding=1965409
@@ -74,140 +91,137 @@ First columns are: running total, address, pss
 >  2641394 r@0x284e518  pss=675985  padding=352  size_without_padding=675633
                source_path= 	object_path=
                flags={}  name=** merge strings
- 3431298 d@0x2c17740  pss=789904  padding=0  size_without_padding=789904
+42823401 d@0x2ddc608  pss=1065132  padding=1065132  size_without_padding=0
+             source_path= 	object_path=
+             flags={}  name=** symbol gap 3 (end of section)
+43613305 d@0x2c17740  pss=789904  padding=0  size_without_padding=789904
              source_path=third_party/container.c 	object_path=third_party/WebKit.a/ContiguousContainer.o
              flags={}  name=chrome::mojom::FieldTrialRecorderProxy [vtable]
- 3500422 t@0x28f1e0   pss=69124  padding=4  size_without_padding=69120
+43714905 d@0x2dffd88  pss=101600  padding=101600  size_without_padding=0
+             source_path= 	object_path=
+             flags={}  name=** symbol gap 3 (end of section)
+43784029 t@0x28f1e0   pss=69124  padding=4  size_without_padding=69120
              source_path=third_party/icu/ucnv_ext.c 	object_path=third_party/icu/icuuc/ucnv_ext.o
              flags={unlikely}  name=foo_bar
- 3510180 t@Group      pss=9758  padding=9758  size_without_padding=0  count=2
-             source_path= 	object_path=
-             flags={}  name=** symbol gaps
->     5718 t@0x28f000   pss=5718  padding=5718  size_without_padding=0
-               source_path=third_party/icu/ucnv_ext.c 	object_path=third_party/icu/icuuc/ucnv_ext.o
-               flags={}  name=** symbol gap 0
->     9758 t@0x2a1000   pss=4040  padding=4040  size_without_padding=0
-               source_path=third_party/container.c 	object_path=third_party/WebKit.a/ContiguousContainer.o
-               flags={}  name=** symbol gap 1
- 3510628 t@0x28f000   pss=448  padding=0  size_without_padding=448
+43784477 t@0x28f000   pss=448  padding=0  size_without_padding=448
              source_path=third_party/icu/ucnv_ext.c 	object_path=third_party/icu/icuuc/ucnv_ext.o
              flags={}  name=ucnv_extMatchFromU
                         full_name=ucnv_extMatchFromU(int const*, int, unsigned short const*, int, unsigned short const*, int, unsigned int*, signed char, signed char)
- 3510780 d@0x2de7008  pss=152  padding=0  size_without_padding=152
+43784629 d@0x2de7008  pss=152  padding=0  size_without_padding=152
              source_path=third_party/container.c 	object_path=third_party/WebKit.a/ContiguousContainer.o
              flags={rel}  name=base::android::kBaseRegisteredMethods
- 3510874 t@0x2a1000   pss=94  padding=0  size_without_padding=94
+43784723 t@0x2a1000   pss=94  padding=0  size_without_padding=94
              source_path=third_party/container.c 	object_path=third_party/WebKit.a/ContiguousContainer.o
              flags={anon}  name=blink::PaintChunker::releasePaintChunks [clone .part.1]
                         full_name=blink::PaintChunker::releasePaintChunks() [clone .part.1]
- 3510930 d@0x2c176f0  pss=56  padding=0  size_without_padding=56
+43784779 d@0x2c176f0  pss=56  padding=0  size_without_padding=56
              source_path=third_party/icu/ucnv_ext.c 	object_path=third_party/icu/icuuc/ucnv_ext.o
              flags={}  name=ChromeMainDelegate [vtable]
- 3510986 d@0x2cd8500  pss=56  padding=0  size_without_padding=56
+43784835 d@0x2cd8500  pss=56  padding=0  size_without_padding=56
              source_path=third_party/paint.cc 	object_path=third_party/WebKit.a/PaintChunker.o
              flags={}  name=ChromeMainDelegateAndroid [vtable]
- 3511042 t@0x28d910   pss=56  padding=0  size_without_padding=56
+43784891 t@0x28d910   pss=56  padding=0  size_without_padding=56
              source_path=base/page_allocator.cc 	object_path=base/base/page_allocator.o
              flags={startup}  name=_GLOBAL__sub_I_bbr_sender.cc
- 3511097 r@0x28f3450  pss=55  padding=7  size_without_padding=48
+43784946 r@0x28f3450  pss=55  padding=7  size_without_padding=48
              source_path=third_party/paint.cc 	object_path=third_party/WebKit.a/PaintChunker.o
              flags={anon}  name=kAnimationFrameTimeHistogramClassPath
- 3511121 t@0x2a0000   pss=24  padding=32  size_without_padding=16
+43784970 t@0x2a0000   pss=24  padding=32  size_without_padding=16
              source_path=third_party/icu/ucnv_ext.c 	object_path=third_party/icu/icuuc/ucnv_ext.o
              flags={2 aliases}  name=BazAlias
                         full_name=BazAlias(bool)
- 3511145 t@0x2a0000   pss=24  padding=32  size_without_padding=16
+43784994 t@0x2a0000   pss=24  padding=32  size_without_padding=16
              source_path= 	object_path=
              flags={2 aliases}  name=blink::ContiguousContainerBase::shrinkToFit
                         full_name=blink::ContiguousContainerBase::shrinkToFit()
- 3511189 r@0x284e370  pss=44  padding=4  size_without_padding=40
+43785038 r@0x284e370  pss=44  padding=4  size_without_padding=40
              source_path=base/page_allocator.cc 	object_path=base/base/page_allocator.o
              flags={}  name=Name
- 3511227 t@0x28d964   pss=38  padding=0  size_without_padding=38
+43785076 t@0x28d964   pss=38  padding=0  size_without_padding=38
              source_path=base/page_allocator.cc 	object_path=base/base/page_allocator.o
              flags={}  name=extFromUUseMapping
                         full_name=extFromUUseMapping(signed char, unsigned int, int)
- 3511259 d@0x2cd84e0  pss=32  padding=16  size_without_padding=16
+43785108 d@0x2cd84e0  pss=32  padding=16  size_without_padding=16
              source_path= 	object_path=third_party/gvr-android-sdk/libgvr_shim_static_arm.a/libcontroller_api_impl.a_controller_api_impl.o
              flags={}  name=.Lswitch.table.45
- 3511291 r@0x284e398  pss=32  padding=0  size_without_padding=32
+43785140 r@0x284e398  pss=32  padding=0  size_without_padding=32
              source_path=third_party/container.c 	object_path=third_party/WebKit.a/ContiguousContainer.o
              flags={}  name=chrome::mojom::FilePatcher::Name_
- 3511323 t@0x28d98a   pss=32  padding=0  size_without_padding=32
+43785172 t@0x28d98a   pss=32  padding=0  size_without_padding=32
              source_path=base/page_allocator.cc 	object_path=base/base/page_allocator.o
              flags={}  name=extFromUUseMapping
                         full_name=extFromUUseMapping(aj, int)
- 3511351 t@0x28f1c8   pss=28  padding=8  size_without_padding=20
+43785200 t@0x28f1c8   pss=28  padding=8  size_without_padding=20
              source_path=third_party/icu/ucnv_ext.c 	object_path=third_party/icu/icuuc/ucnv_ext.o
              flags={startup}  name=_GLOBAL__sub_I_SkDeviceProfile.cpp
- 3511379 t@0x28d948   pss=28  padding=0  size_without_padding=28
+43785228 t@0x28d948   pss=28  padding=0  size_without_padding=28
              source_path=base/page_allocator.cc 	object_path=base/base/page_allocator.o
              flags={startup}  name=_GLOBAL__sub_I_pacing_sender.cc
- 3511407 t@0x2a0020   pss=28  padding=4  size_without_padding=24
+43785256 t@0x2a0020   pss=28  padding=4  size_without_padding=24
              source_path=third_party/container.c 	object_path=third_party/WebKit.a/ContiguousContainer.o
              flags={}  name=blink::ContiguousContainerBase::ContiguousContainerBase
                         full_name=blink::ContiguousContainerBase::ContiguousContainerBase(blink::ContiguousContainerBase&&)
- 3511431 d@0x2c17728  pss=24  padding=0  size_without_padding=24
+43785280 d@0x2c17728  pss=24  padding=0  size_without_padding=24
              source_path=third_party/icu/ucnv_ext.c 	object_path=third_party/icu/icuuc/ucnv_ext.o
              flags={}  name=chrome::mojom::FieldTrialRecorder [vtable]
- 3511455 d@0x2cd8538  pss=24  padding=0  size_without_padding=24
+43785304 d@0x2cd8538  pss=24  padding=0  size_without_padding=24
              source_path=base/page_allocator.cc 	object_path=base/base/page_allocator.o
              flags={}  name=mojo::MessageReceiver [vtable]
- 3511471 t@0x28d900   pss=16  padding=0  size_without_padding=16
+43785320 t@0x28d900   pss=16  padding=0  size_without_padding=16
              source_path=base/page_allocator.cc 	object_path=base/base/page_allocator.o
              flags={startup}  name=_GLOBAL__sub_I_page_allocator.cc
- 3511475 t@0x2a0010   pss=4  padding=0  size_without_padding=12
+43785324 t@0x2a0010   pss=4  padding=0  size_without_padding=12
              source_path=third_party/fft_float.cc 	object_path=third_party/ffmpeg/libffmpeg_internal.a/fft_float.o
              flags={3 aliases}  name=BarAlias
                         full_name=BarAlias()
- 3511479 t@0x2a0010   pss=4  padding=0  size_without_padding=12
+43785328 t@0x2a0010   pss=4  padding=0  size_without_padding=12
              source_path=third_party/fft_float.cc 	object_path=third_party/ffmpeg/libffmpeg_internal.a/fft_float.o
              flags={3 aliases}  name=FooAlias
                         full_name=FooAlias()
- 3511483 t@0x2a0010   pss=4  padding=0  size_without_padding=12
+43785332 t@0x2a0010   pss=4  padding=0  size_without_padding=12
              source_path=third_party/{shared}/2 	object_path=third_party/{shared}/2
              flags={3 aliases}  name=blink::ContiguousContainerBase::shrinkToFit [clone .part.1234] [clone .isra.2]
                         full_name=blink::ContiguousContainerBase::shrinkToFit() [clone .part.1234] [clone .isra.2]
- 3511495 d@0x2cd8550  pss=12  padding=0  size_without_padding=12
+43785344 d@0x2cd8550  pss=12  padding=0  size_without_padding=12
              source_path=base/page_allocator.cc 	object_path=base/base/page_allocator.o
              flags={}  name=kMethodsAnimationFrameTimeHistogram
- 3511506 r@0x284e364  pss=11  padding=3  size_without_padding=8
+43785352 r@0x284e364  pss=8  padding=0  size_without_padding=8
              source_path=base/page_allocator.cc 	object_path=base/base/page_allocator.o
- 3511514 d@0x2cd84f0  pss=8  padding=0  size_without_padding=8
+43785360 d@0x2cd84f0  pss=8  padding=0  size_without_padding=8
              source_path= 	object_path=third_party/gvr-android-sdk/libgvr_shim_static_arm.a/libport_android_jni.a_jni_utils.o
              flags={anon}  name=kSystemClassPrefixes
- 3511518 d@0x2de70a4  pss=4  padding=0  size_without_padding=4
+43785364 d@0x2de70a4  pss=4  padding=0  size_without_padding=4
              source_path=third_party/container.c 	object_path=third_party/WebKit.a/ContiguousContainer.o
              flags={anon,rel.loc}  name=base::android::g_library_version_number
- 3511522 d@0x2de70a0  pss=4  padding=0  size_without_padding=4
+43785368 d@0x2de70a0  pss=4  padding=0  size_without_padding=4
              source_path=third_party/container.c 	object_path=third_party/WebKit.a/ContiguousContainer.o
              flags={anon}  name=base::android::g_renderer_histogram_code
- 3511526 r@0x28f3480  pss=4  padding=0  size_without_padding=4
+43785372 r@0x28f3480  pss=4  padding=0  size_without_padding=4
              source_path=third_party/paint.cc 	object_path=third_party/WebKit.a/PaintChunker.o
              flags={anon}  name=blink::CSSValueKeywordsHash::findValueImpl::value_word_list
                         full_name=blink::CSSValueKeywordsHash::findValueImpl(char const*, unsigned int)::value_word_list
- 3511530 d@0x2de7000  pss=4  padding=0  size_without_padding=4
+43785376 d@0x2de7000  pss=4  padding=0  size_without_padding=4
              source_path=base/page_allocator.cc 	object_path=base/base/page_allocator.o
              flags={}  name=google::protobuf::internal::pLinuxKernelCmpxchg
- 3511534 d@0x2de7004  pss=4  padding=0  size_without_padding=4
+43785380 d@0x2de7004  pss=4  padding=0  size_without_padding=4
              source_path=third_party/container.c 	object_path=third_party/WebKit.a/ContiguousContainer.o
              flags={}  name=google::protobuf::internal::pLinuxKernelMemoryBarrier
- 3511534 b@0x0        pss=262144  padding=0  size_without_padding=262144
+43785380 b@0x0        pss=262144  padding=0  size_without_padding=262144
              source_path=third_party/fft_float.cc 	object_path=third_party/ffmpeg/libffmpeg_internal.a/fft_float.o
              flags={}  name=ff_cos_131072
- 3511534 b@0x0        pss=131072  padding=0  size_without_padding=131072
+43785380 b@0x0        pss=131072  padding=0  size_without_padding=131072
              source_path=third_party/fft_fixed.cc 	object_path=third_party/ffmpeg/libffmpeg_internal.a/fft_fixed.o
              flags={}  name=ff_cos_131072_fixed
- 3511534 b@0x0        pss=131072  padding=0  size_without_padding=131072
+43785380 b@0x0        pss=131072  padding=0  size_without_padding=131072
              source_path=third_party/fft_float.cc 	object_path=third_party/ffmpeg/libffmpeg_internal.a/fft_float.o
              flags={}  name=ff_cos_65536
- 3511534 b@0x2dffe80  pss=200  padding=196  size_without_padding=4
+43785380 b@0x2dffe80  pss=200  padding=196  size_without_padding=4
              source_path=third_party/icu/ucnv_ext.c 	object_path=third_party/icu/icuuc/ucnv_ext.o
              flags={}  name=SaveHistogram::atomic_histogram_pointer
                         full_name=SaveHistogram(_JNIEnv*, base::android::JavaParamRef<_jobject*> const&, base::android::JavaParamRef<_jstring*> const&, base::android::JavaParamRef<_jlongArray*> const&, int)::atomic_histogram_pointer
- 3511534 b@0x2dffda0  pss=28  padding=0  size_without_padding=28
+43785380 b@0x2dffda0  pss=28  padding=0  size_without_padding=28
              source_path=third_party/icu/ucnv_ext.c 	object_path=third_party/icu/icuuc/ucnv_ext.o
              flags={}  name=g_chrome_content_browser_client
- 3511534 b@0x2dffe84  pss=4  padding=0  size_without_padding=4
+43785380 b@0x2dffe84  pss=4  padding=0  size_without_padding=4
              source_path=third_party/icu/ucnv_ext.c 	object_path=third_party/icu/icuuc/ucnv_ext.o
              flags={anon}  name=g_AnimationFrameTimeHistogram_clazz