Move forceSRGB to SkCommonFlags.

This fixes a duplicate symbol problem with the iOS build.

Add common forceSRGB flag.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2019073002

Review-Url: https://codereview.chromium.org/2019073002
diff --git a/bench/nanobench.cpp b/bench/nanobench.cpp
index 6af54d8..55ef34e 100644
--- a/bench/nanobench.cpp
+++ b/bench/nanobench.cpp
@@ -123,8 +123,6 @@
 DEFINE_string(benchType,  "",
         "Apply usual --match rules to bench type: micro, recording, playback, skcodec, etc.");
 
-DEFINE_bool(forceSRGB, false, "Force SRGB for imageinfos");
-
 static double now_ms() { return SkTime::GetNSecs() * 1e-6; }
 
 static SkString humanize(double ms) {
diff --git a/dm/DM.cpp b/dm/DM.cpp
index 2ac2f20..b10de5e 100644
--- a/dm/DM.cpp
+++ b/dm/DM.cpp
@@ -71,7 +71,6 @@
 DEFINE_int32(shards, 1, "We're splitting source data into this many shards.");
 DEFINE_int32(shard,  0, "Which shard do I run?");
 DEFINE_bool(simpleCodec, false, "Only decode images to native scale");
-DEFINE_bool(forceSRGB, false, "Force SRGB for imageinfos");
 
 using namespace DM;
 using sk_gpu_test::GrContextFactory;
diff --git a/tools/flags/SkCommonFlags.cpp b/tools/flags/SkCommonFlags.cpp
index 1caffd5..3da5efe 100644
--- a/tools/flags/SkCommonFlags.cpp
+++ b/tools/flags/SkCommonFlags.cpp
@@ -13,6 +13,8 @@
 DEFINE_bool(dryRun, false,
             "just print the tests that would be run, without actually running them.");
 
+DEFINE_bool(forceSRGB, false, "Force SRGB for imageinfos");
+
 DEFINE_bool(gpu, true, "master switch for running GPU-bound work.");
 
 DEFINE_string(images, "", "List of images and/or directories to decode. A directory with no images"
diff --git a/tools/flags/SkCommonFlags.h b/tools/flags/SkCommonFlags.h
index ddd0fc8..b7eaca4 100644
--- a/tools/flags/SkCommonFlags.h
+++ b/tools/flags/SkCommonFlags.h
@@ -14,6 +14,7 @@
 
 DECLARE_bool(cpu);
 DECLARE_bool(dryRun);
+DECLARE_bool(forceSRGB);
 DECLARE_bool(gpu);
 DECLARE_string(images);
 DECLARE_string(colorImages);