Initialize all ImageCandidate's member variables

While re-reading the code, I noticed that some of ImageCandidate's member variables
are not initialized as they should.
This CL fixes that.

BUG=

Review URL: https://codereview.chromium.org/311053011

git-svn-id: svn://svn.chromium.org/blink/trunk@175758 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Source/core/html/parser/HTMLSrcsetParser.h

@@ -74,6 +74,8 @@ public:
 
     ImageCandidate()
         : m_density(1.0)
+        , m_resourceWidth(UninitializedDescriptor)
+        , m_originAttribute(SrcsetOrigin)
     {
     }
 

third_party/WebKit/Source/core/html/parser/HTMLSrcsetParserTest.cpp

@@ -20,6 +20,15 @@ typedef struct {
     int outputResourceWidth;
 } TestCase;
 
+TEST(ImageCandidateTest, Basic)
+{
+    ImageCandidate candidate;
+    ASSERT_EQ(candidate.density(), 1);
+    ASSERT_EQ(candidate.resourceWidth(), -1);
+    ASSERT_EQ(candidate.srcOrigin(), false);
+
+}
+
 TEST(HTMLSrcsetParserTest, Basic)
 {
     TestCase testCases[] = {