Refactor OriginTrialPolicy to be an abstract interface in content/public/common

chrome/app/chrome_main_delegate.cc

Index: chrome/app/chrome_main_delegate.cc
diff --git a/chrome/app/chrome_main_delegate.cc b/chrome/app/chrome_main_delegate.cc
index 22ed2aa8b65964e7a3610be177e29f07a6fe52c1..1c0852bc0ceb830a4337a2bd853f62154bf0abdb 100644
--- a/chrome/app/chrome_main_delegate.cc
+++ b/chrome/app/chrome_main_delegate.cc
@@ -636,12 +636,7 @@ bool ChromeMainDelegate::BasicStartupComplete(int* exit_code) {
   }
 #endif
 
-  if (command_line.HasSwitch(switches::kOriginTrialPublicKey)) {
-    chrome_content_client_.origin_trial_key_manager()
-        ->SetPublicKeyFromASCIIString(
-            command_line.GetSwitchValueASCII(switches::kOriginTrialPublicKey));
-  }
-
+  chrome_content_client_.InitializeOriginTrialPolicy();

[jochen (gone - plz use gerrit), 2016/06/20 11:44:56]

chrome shouldn't call content's embedder APIs. Why aren't you just invoking a
method on ChromeOriginTrialPolicy?

[iclelland, 2016/06/20 18:08:40]

This was a temporary situation (as a result of refactoring the three CLs to make
this one first)

You can see in https://codereview.chromium.org/2047683002/patch/60001/70011 that
this call is moved to render_thread_impl.cc, and called from content/.

I can fix the layering violation here, and update the next CL to undo that, or I
can merge the two CLs so it never happens. I had split them up to (hopefully)
make review easier, but I can always re-combine them.

[iclelland, 2016/06/21 03:33:34]

I think the only reason I hadn't made InitializeOriginTrialPolicy a method on
OriginTrialPolicy before is that I was making everything about OriginTrialPolicy
const, by Sorin's suggestion, and so the RenderThreadImpl didn't have a way to
get a non-const OriginTrialPolicy object to initialize it. I've added a patch to
this CL that adds a non-const GetOriginTrialPolicy() method, which can be used
for initialization. The TrialTokenValidator still uses the const version, to
make it clear that it's not modifying either the ContentClient or the
OriginTrialPolicy.

   content::SetContentClient(&chrome_content_client_);
 
 #if defined (OS_CHROMEOS)