Fix iOS build by centralizing --writePath.

CQ_EXTRA_TRYBOTS=tryserver.skia:Build-Mac10.7-Clang-Arm7-Debug-iOS-Trybot

BUG=skia:
R=mtklein@google.com

Author: mtklein@chromium.org

Review URL: https://codereview.chromium.org/452633002
diff --git a/bench/nanobench.cpp b/bench/nanobench.cpp
index 245aa0e..a5353aa 100644
--- a/bench/nanobench.cpp
+++ b/bench/nanobench.cpp
@@ -33,7 +33,7 @@
 
 static const int kAutoTuneLoops = -1;
 
-static const int kDefaultLoops = 
+static const int kDefaultLoops =
 #ifdef SK_DEBUG
     1;
 #else
@@ -50,8 +50,6 @@
 
 DEFINE_int32(loops, kDefaultLoops, loops_help_txt().c_str());
 
-DEFINE_string2(writePath, w, "", "If set, write benches here as .pngs.");
-
 DEFINE_int32(samples, 10, "Number of samples to measure for each bench.");
 DEFINE_int32(overheadLoops, 100000, "Loops to estimate timer overhead.");
 DEFINE_double(overheadGoal, 0.0001,
diff --git a/dm/DMWriteTask.cpp b/dm/DMWriteTask.cpp
index 5435087..b8ce318 100644
--- a/dm/DMWriteTask.cpp
+++ b/dm/DMWriteTask.cpp
@@ -8,7 +8,6 @@
 #include "SkStream.h"
 #include "SkString.h"
 
-DEFINE_string2(writePath, w, "", "If set, write GMs here as .pngs.");
 DEFINE_bool(writePngOnly, false, "If true, don't encode raw bitmap after .png data.  "
                                  "This means -r won't work, but skdiff will still work fine.");
 
diff --git a/tools/flags/SkCommonFlags.cpp b/tools/flags/SkCommonFlags.cpp
index 80ef2bf..4d08ba6 100644
--- a/tools/flags/SkCommonFlags.cpp
+++ b/tools/flags/SkCommonFlags.cpp
@@ -52,3 +52,5 @@
 DEFINE_bool2(verbose, v, false, "enable verbose output from the test driver.");
 
 DEFINE_bool2(veryVerbose, V, false, "tell individual tests to be verbose.");
+
+DEFINE_string2(writePath, w, "", "If set, write bitmaps here as .pngs.");
diff --git a/tools/flags/SkCommonFlags.h b/tools/flags/SkCommonFlags.h
index 4abf201..b45ef07 100644
--- a/tools/flags/SkCommonFlags.h
+++ b/tools/flags/SkCommonFlags.h
@@ -26,5 +26,6 @@
 DECLARE_string(resourcePath);
 DECLARE_bool(verbose);
 DECLARE_bool(veryVerbose);
+DECLARE_string(writePath);
 
 #endif