Resize IPC input buffer to fit the next message.

ipc/ipc_channel_reader.h

Index: ipc/ipc_channel_reader.h
diff --git a/ipc/ipc_channel_reader.h b/ipc/ipc_channel_reader.h
index 3f3fc457954492b05b2a001d460fccc423052444..46775226f9a13a4d2d49ba611c349e50506f98d9 100644
--- a/ipc/ipc_channel_reader.h
+++ b/ipc/ipc_channel_reader.h
@@ -127,6 +127,8 @@ class IPC_EXPORT ChannelReader : public SupportsAttachmentBrokering,
  private:
   FRIEND_TEST_ALL_PREFIXES(ChannelReaderTest, AttachmentAlreadyBrokered);
   FRIEND_TEST_ALL_PREFIXES(ChannelReaderTest, AttachmentNotYetBrokered);
+  FRIEND_TEST_ALL_PREFIXES(ChannelReaderTest, ResizeOverflowBuffer);
+  FRIEND_TEST_ALL_PREFIXES(ChannelReaderTest, InvalidMessageSize);
 
   typedef std::set<BrokerableAttachment::AttachmentId> AttachmentIdSet;
 
@@ -156,6 +158,9 @@ class IPC_EXPORT ChannelReader : public SupportsAttachmentBrokering,
   void StartObservingAttachmentBroker();
   void StopObservingAttachmentBroker();
 
+  // Checks that |size| is a valid message size. Has side effects if it's not.

[jam, 2015/09/30 14:18:16]

nit: why does it need to mention an internal impl' detail of resetting the
buffer?

[Dmitry Skiba, 2015/09/30 15:32:35]

Well, the function is named 'Check', so personally I wouldn't expect it to have
side effects (although lack of const-ness gives a hint). And I couldn't come up
with a better verb. Naming is hard...

+  bool CheckMessageSize(size_t size);
+
   Listener* listener_;
 
   // We read from the pipe into this buffer. Managed by DispatchInputData, do