Move ImageFetcher to its own target.

ios/chrome/browser/net/BUILD.gn

Index: ios/chrome/browser/net/BUILD.gn
diff --git a/ios/chrome/browser/net/BUILD.gn b/ios/chrome/browser/net/BUILD.gn
index 4b26d7f72c7596c18f820d93b31ee35db071b584..b2d37fae8e6271d30c07c680da571a72596c4046 100644
--- a/ios/chrome/browser/net/BUILD.gn
+++ b/ios/chrome/browser/net/BUILD.gn
@@ -14,8 +14,6 @@ source_set("net") {
     "crl_set_fetcher.h",
     "http_server_properties_manager_factory.cc",
     "http_server_properties_manager_factory.h",
-    "image_fetcher.h",
-    "image_fetcher.mm",
     "ios_chrome_http_user_agent_settings.h",
     "ios_chrome_http_user_agent_settings.mm",
     "ios_chrome_network_delegate.cc",
@@ -43,19 +41,34 @@ source_set("net") {
     "//ios/chrome/browser",
     "//ios/chrome/browser/browser_state",
     "//ios/chrome/browser/browsing_data",
-    "//ios/chrome/browser/webp_transcode",
     "//ios/net",
     "//ios/web",
     "//net",
     "//net:extras",
     "//url",
   ]
+  public_deps = [
+    ":image_fetcher",

[sdefresne, 2016/11/22 14:38:19]

Can you add a TODO to remove this public_deps (or move it to deps) once the
downstream code has been changed to not require it?

[gambard, 2016/11/22 14:44:13]

Done.

+  ]
   allow_circular_includes_from = [
     "//ios/chrome/browser",
     "//ios/chrome/browser/browser_state",
   ]
 }
 
+source_set("image_fetcher") {
+  sources = [
+    "image_fetcher.h",
+    "image_fetcher.mm",
+  ]
+  deps = [
+    "//base",
+    "//ios/chrome/browser/webp_transcode",
+    "//ios/web",
+    "//net",
+  ]
+}
+
 source_set("test_support") {
   testonly = true
   sources = [
@@ -63,7 +76,7 @@ source_set("test_support") {
     "mock_image_fetcher.mm",
   ]
   deps = [
-    ":net",
+    ":image_fetcher",
     "//testing/gmock",
   ]
 }
@@ -77,6 +90,7 @@ source_set("unit_tests") {
     "retryable_url_fetcher_unittest.mm",
   ]
   deps = [
+    ":image_fetcher",
     ":net",
     "//base",
     "//base/test:test_support",