PPAPI: Fix raymes's review comments I missed

PPAPI: Fix raymes's review comments I missed

from https://codereview.chromium.org/589213003/

BUG=401761
TBR=raymes@chromium.org

[dmichael (off chromium), 2014-09-24 16:15:16]

The CQ bit was checked by dmichael@chromium.org

[commit-bot: I haz the power, 2014-09-24 16:15:44]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/596343003/1

[dmichael (off chromium), 2014-09-24 16:16:03]

The CQ bit was checked by dmichael@chromium.org

[dmichael (off chromium), 2014-09-24 16:16:03]

The CQ bit was unchecked by dmichael@chromium.org

[dmichael (off chromium), 2014-09-24 23:12:11]

The CQ bit was checked by dmichael@chromium.org

[commit-bot: I haz the power, 2014-09-24 23:13:50]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/596343003/1

[raymes, 2014-09-24 23:52:46]

lgtm

[commit-bot: I haz the power, 2014-09-25 00:05:58]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-09-25 00:05:59]

Failed to apply patch for content/renderer/pepper/message_channel.cc:
While running git apply --index -3 -p1;
  error: patch failed: content/renderer/pepper/message_channel.cc:166
  Falling back to three-way merge...
  Applied patch to 'content/renderer/pepper/message_channel.cc' with conflicts.
  U content/renderer/pepper/message_channel.cc

Patch:       content/renderer/pepper/message_channel.cc
Index: content/renderer/pepper/message_channel.cc
diff --git a/content/renderer/pepper/message_channel.cc
b/content/renderer/pepper/message_channel.cc
index
df56988af09c8de1b2882f0e17abd4d835d72c1c..2ce6009fcc4370d29723c12e2117c33b8644f1b5
100644
--- a/content/renderer/pepper/message_channel.cc
+++ b/content/renderer/pepper/message_channel.cc
@@ -166,9 +166,9 @@ void MessageChannel::Start() {
   if (dispatcher)
     dispatcher->AddSyncMessageStatusObserver(this);
 
-  // We can't drain the JS message queue directly
-  // since we haven't finished initializing the PepperWebPluginImpl yet, so
-  // the plugin isn't available in the DOM.
+  // We can't drain the JS message queue directly since we haven't finished
+  // initializing the PepperWebPluginImpl yet, so the plugin isn't available in
+  // the DOM.
   DrainJSMessageQueueSoon();
 
   plugin_message_queue_state_ = SEND_DIRECTLY;
@@ -209,6 +209,7 @@ void MessageChannel::BeginBlockOnSyncMessage() {
 }
 
 void MessageChannel::EndBlockOnSyncMessage() {
+  DCHECK_GT(blocking_message_depth_, 0);
   --blocking_message_depth_;
   if (!blocking_message_depth_)
     DrainJSMessageQueueSoon();

[dmichael (off chromium), 2014-09-25 15:40:36]

https://codereview.chromium.org/589213003/ got reverted and this didn't apply.

I'll just put it in the re-land of https://codereview.chromium.org/589213003/
 and close this CL.