Add WARN_UNUSED_RESULT to BytesConsumer read methods.

BUG=610195

Review-Url: https://codereview.chromium.org/2319033002
Cr-Commit-Position: refs/heads/master@{#418506}

third_party/WebKit/Source/modules/fetch/BytesConsumer.h

@@ -9,6 +9,7 @@
 #include "platform/blob/BlobData.h"
 #include "platform/heap/Handle.h"
 #include "platform/network/EncodedFormData.h"
+#include "wtf/Compiler.h"
 #include "wtf/PassRefPtr.h"
 #include "wtf/text/WTFString.h"
 
@@ -82,7 +83,7 @@ public:
     // Returns Error when errored.
     // |buffer| can be null if |size| is 0.
     // |*readSize| will be set to 0 if not readable.
-    virtual Result read(char* buffer, size_t /* size */, size_t* readSize);
+    virtual Result read(char* buffer, size_t /* size */, size_t* readSize) WARN_UNUSED_RESULT;
 
     // Begins a two-phase read. On success, the function stores a buffer
     // that contains the read data of length |*available| into |*buffer|.
@@ -98,10 +99,10 @@ public:
     //
     // |*buffer| will be set to null and |*available| will be set to 0 if not
     // readable.
-    virtual Result beginRead(const char** buffer, size_t* available) = 0;
+    virtual Result beginRead(const char** buffer, size_t* available) WARN_UNUSED_RESULT = 0;
 
     // Ends a two-phase read.
-    virtual Result endRead(size_t readSize) = 0;
+    virtual Result endRead(size_t readSize) WARN_UNUSED_RESULT = 0;
 
     // Drains the data as a BlobDataHandle.
     // When this function returns a non-null value, the returned blob handle

third_party/WebKit/Source/modules/fetch/BytesConsumerTestUtil.cpp

@@ -209,7 +209,10 @@ void BytesConsumerTestUtil::TwoPhaseReader::onStateChange()
             // because of the same reasons as Reader::onStateChange.
             size_t read = std::max(static_cast<size_t>(3), available);
             m_data.append(buffer, read);
-            m_consumer->endRead(read);
+            if (m_consumer->endRead(read) != BytesConsumer::Result::Ok) {
+                m_result = BytesConsumer::Result::Error;
+                return;
+            }
             break;
         }
         case BytesConsumer::Result::ShouldWait:

third_party/WebKit/Source/modules/fetch/FetchDataLoader.cpp

@@ -63,7 +63,10 @@ public:
             switch (m_consumer->beginRead(&buffer, &available)) {
             case BytesConsumer::Result::Ok:
                 m_blobData->appendBytes(buffer, available);
-                m_consumer->endRead(available);
+                if (m_consumer->endRead(available) != BytesConsumer::Result::Ok) {
+                    m_client->didFetchDataLoadFailed();
+                    return;
+                }
                 break;
             case BytesConsumer::Result::ShouldWait:
                 return;
@@ -125,14 +128,18 @@ public:
                 if (available > 0) {
                     unsigned bytesAppended = m_rawData->append(buffer, available);
                     if (!bytesAppended) {
-                        m_consumer->endRead(0);
+                        auto unused = m_consumer->endRead(0);
+                        ALLOW_UNUSED_LOCAL(unused);
                         m_consumer->cancel();
                         m_client->didFetchDataLoadFailed();
                         return;
                     }
                     DCHECK_EQ(bytesAppended, available);
                 }
-                m_consumer->endRead(available);
+                if (m_consumer->endRead(available) != BytesConsumer::Result::Ok) {
+                    m_client->didFetchDataLoadFailed();
+                    return;
+                }
                 break;
             case BytesConsumer::Result::ShouldWait:
                 return;
@@ -185,7 +192,10 @@ public:
             case BytesConsumer::Result::Ok:
                 if (available > 0)
                     m_builder.append(m_decoder->decode(buffer, available));
-                m_consumer->endRead(available);
+                if (m_consumer->endRead(available) != BytesConsumer::Result::Ok) {
+                    m_client->didFetchDataLoadFailed();
+                    return;
+                }
                 break;
             case BytesConsumer::Result::ShouldWait:
                 return;
@@ -248,7 +258,11 @@ public:
             switch (m_consumer->beginRead(&buffer, &available)) {
             case BytesConsumer::Result::Ok:
                 m_outStream->addData(buffer, available);
-                m_consumer->endRead(available);
+                if (m_consumer->endRead(available) != BytesConsumer::Result::Ok) {
+                    m_outStream->abort();
+                    m_client->didFetchDataLoadFailed();
+                    return;
+                }
                 needToFlush = true;
                 break;
             case BytesConsumer::Result::ShouldWait: